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How to Warm Up a New Email Domain or IP for Event Marketing Success

Email is the lifeblood of event marketing – whether you’re promoting a B2B industry conference, a B2C music festival, a trade show, or a local independent event, getting your emails into recipients’ inboxes is critical. When you start sending from a new email domain or IP address, you can’t just hit “send” on thousands of invites or announcements and expect instant success. Mailbox providers treat new senders with caution. If they see a sudden flood of emails from an unknown domain or IP, they will likely divert your messages to spam or block them entirely. This is why “warming up” a new email domain or IP is essential. Warming up means slowly ramping up your email sending volume and establishing a positive sender reputation before your big send. In simple terms, it’s the process of gradually increasing the number of emails you send over time from a new domain/IP, allowing internet service providers (ISPs) to observe that you’re a legitimate sender and not a spammer.


For event marketers in corporate settings, trade show organisers, independent promoters, and agencies alike, proper domain and IP warm-up is a non-negotiable step to email marketing success. It applies to both B2B and B2C events – from corporate conference invitations to consumer concert promotions – because in 2025 mailbox providers for businesses and consumers use similar advanced filters. In fact, many business email addresses are hosted by providers like Gmail, Outlook, or Yahoo, so B2B senders must follow the same warm-up process as B2C senders. Skipping warm-up can result in poor deliverability: high bounce rates, emails landing in spam folders, or being throttled by ISPs. Conversely, a proper warm-up builds a good sender reputation over time, meaning emails land in the inbox rather than spam. The guide below will walk you through why warming up is important and how to do it step by step – from technical setup (SPF, DKIM, DMARC) to sending strategy, list management, segmentation, automation, reputation monitoring, preference centres, and avoiding pitfalls like spam traps and blacklists. Let’s dive in!


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1. Configure Your Domain with Proper Email Authentication (SPF, DKIM, DMARC)


Before sending a single campaign, set up your new email domain correctly with DNS records to authenticate your emails. Email authentication proves to mailbox providers that your messages are legitimate and truly from you, which is the foundation for a good sender reputation. There are three critical DNS records to configure:


  • SPF (Sender Policy Framework): SPF allows you to specify which mail servers are permitted to send email on behalf of your domain. By creating an SPF TXT record in your DNS, you list your sending IPs or email service providers. Mailbox providers will check this to ensure the server sending your event emails is authorised. If the server isn’t in your SPF record, the email can fail SPF and be flagged.

    Action: Publish an SPF record that includes all your email sources (e.g. your marketing platform’s SPF include). For example, an SPF record might look like v=spf1 include:your-esp.com -all which tells ISPs that your ESP (email service provider) is allowed to send for your domain.


  • DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails, tied to your domain, that ISPs can verify with a public key in your DNS. Essentially, your email system will “sign” outgoing event emails with a private key, and ISPs use the public key (published as a TXT record) to confirm the message wasn’t altered and truly comes from your domain.

    Action: Generate a DKIM key pair (most email platforms do this for you), publish the public key as a DNS TXT record (often on a selector like default._domainkey.yourdomain.com), and enable DKIM signing in your email platform. This cryptographic authentication reassures providers that your event announcements are legitimate.

  • DMARC (Domain-Based Message Authentication, Reporting & Conformance): 

    DMARC builds on SPF and DKIM by telling ISPs what to do if an email fails authentication and by providing you feedback. With a DMARC policy, you can start in “monitoring” mode (p=none) to collect reports on your domain’s email authentication results, then move to an enforcement policy (p=quarantine or p=reject) once you’re confident only legitimate mail is being sent. DMARC also requires the From: domain to align with the authenticated domain, which improves brand consistency.

    Action: Publish a DMARC TXT record (at _dmarc.yourdomain.com) with at least p=none; rua=mailto:you@yourdomain.com to receive reports. Over time, tighten this to an enforcement policy to prevent spoofing. DMARC isn’t just about policy – it’s a valuable tool to receive feedback on any failures. It helps validate that your messages are truly coming from your domainlearn.microsoft.com and builds trust with ISPs.


Why is all this important?

Without proper SPF, DKIM, and DMARC, your event marketing emails may fail basic security checks and get dumped into spam or rejected. Major mailbox providers have made authentication effectively mandatory for bulk senders – for example, Google, Microsoft and Yahoo require verified authentication for senders to reach inboxes. Authentication also protects your brand/domain from being used by bad actors. In short, setting up these DNS records is step 1 for establishing a positive reputation and is “table stakes” for good deliverability.


Tip:  If your organisation has a primary domain (e.g., yourcompany.com), consider sending event marketing emails from a dedicated subdomain like events.yourcompany.com or mail.yourcompany.com. This way, you isolate your main domain’s reputation from heavy marketing sends. Many experts recommend using separate subdomains for different mail streams (e.g. transactional vs. marketing). For example, a corporate event team might use conf-mail.yourcompany.com for conference invites, protecting the core corporate domain. If something goes awry (say, a spike in spam complaints on an event campaign), it won’t directly harm your ability to deliver critical emails like confirmations or password resets on the main domain. Just be sure to also configure SPF/DKIM/DMARC on whatever subdomain you use for sending.


2. Plan a Gradual Domain/IP Warm-up Strategy


Once your domain is technically sound, you need a plan to ramp up email sending gradually. A warm-up plan helps you avoid the “big bang” blast from a new domain/IP that ISPs distrust. Instead, you’ll slowly increase your sending volume over days and weeks. This gives mailbox providers time to observe consistent, positive engagement from your emails and to build your sender reputation steadily.


Start Small and Send to Your Best Contacts First: In the first days of using a new domain or IP, send only a small number of emails – and send them to your most engaged, highest-quality contacts. These are people who have recently interacted with your emails (opened, clicked) or freshly opted in. Since they are more likely to open and click, they’ll send positive signals to ISPs. For example, you might begin by emailing a tiny segment (say 1%) of your list comprised of past event attendees who always engage, rather than your entire database. This aligns with best practices to “start gradually” so that ISPs see low volume initially and can observe your sending patterns and build trust in the legitimacy of your emails. A new sender’s first impression on mailbox providers is crucial – by emailing those least likely to ignore or mark you as spam, you set a positive baseline.


Follow a Week-by-Week Ramp-up Schedule: A common approach is to increase your sending volume incrementally each week, roughly doubling the volume as long as performance is good. For instance, one sample warm-up schedule for an 8-week period is as follows:

  • Week 1: Send to ~1% of your most engaged subscribers (e.g. a few hundred emails if you have 50k contacts).

  • Week 2: Send to ~2% of your best subscribers (e.g. doubling the count from week 1).

  • Week 3: Send to ~4% of top engaged subscribers.

  • Week 4: Send to ~8% of engaged subscribers.

  • Week 5: Send to ~16%.

  • Week 6: Send to ~32%.

  • Week 7: Send to ~64%.

  • Week 8: Send to 100% of your most engaged subscribers (all of your “top tier” contacts).


After about 8 weeks of this gradual ramp-up, if all has gone well (good opens, low bounces/complaints), you can start easing into sending to the rest of your list (less engaged contacts, older leads, etc.) in larger volumes. By this time, your domain/IP should have a solid reputation from those initial warm-up sends.


Example of a warm-up schedule gradually increasing daily and hourly email volume in stages, as recommended by an email service provider. Starting with around 1,000 emails per day (100/hour) at Stage 1 and ramping up to 250,000 per day by Stage 15 shows how “slow and steady” growth establishes a trusted sending reputation.

Be Consistent – and Don’t Rush: Consistency is key during warm-up. Try to send emails regularly (e.g. daily or weekly as per plan) rather than in erratic bursts. If you warm up for a few days then fall silent for a week, your reputation “momentum” can stall. Mailbox providers reward steady sending patterns. Also, resist the urge to accelerate the warm-up too quickly, even if you’re seeing good engagement.


It typically takes 4–8 weeks to properly warm up a new domain/IP. Give yourself as much runway as possible; more time allows you to send slowly and resolve any issues before your big sends. In event marketing, this means you should start the warm-up phase well in advance of your event announcement or invitation email blast. For example, if you plan to send a massive save-the-date email for a conference in June, begin warming the domain in April or earlier. “Slow and steady wins the race” is the mantra here.


Example – B2B vs. B2C Warm-up: The fundamental warm-up process is similar for B2B and B2C event campaigns. For a B2B example, imagine a trade show organiser launching a new domain for email (e.g. tradeshownews.com). In week 1, they might send a personalised note or early registration offer to a handful of past attendees who are highly likely to respond. In subsequent weeks, they expand to larger groups of professionals who have engaged with their content, gradually including more of their list (maybe older leads or less active subscribers only after a month of warming).


For a B2C example, suppose an independent concert promoter sets up myconcerts.net to send ticket announcements. They could start by emailing a small batch of known fans – those who consistently buy tickets or click emails about similar artists – offering an exclusive pre-sale. Over the next weeks, they’d ramp up to larger audiences (like all subscribers in the city) as the new domain gains credibility. In both cases, the strategy is identical: begin with the “warmest” contacts, then scale up. ISPs for business domains and consumer inboxes alike will penalise you if you jump from 0 to 100,000 emails overnight without history. Warming up ensures both corporate email servers and webmail providers see a gradual, organic increase in volume rather than a red-flag spike.


Monitor During the Warm-up: (We’ll cover monitoring in detail later, but it’s worth noting here.) Keep a close eye on each send’s results during this ramp-up phase. If you notice any troubling signs – e.g., a lot of emails to a particular ISP are going to spam or bouncing – you might adjust your plan (perhaps slow down or temporarily remove that ISP’s addresses from the next send). For instance, if during week 3 you see that Gmail recipients had low opens or many went to spam, you could pause sending to Gmail addresses in week 4 and focus on other domains while investigating. The idea is to identify issues early and not plow ahead increasing volume if there’s a deliverability problem. We’ll discuss metrics and tools to use for this monitoring in a later section.


Finally, remember that warming up both the domain and IP address may be necessary. If you are on a new dedicated IP, you’re essentially warming that IP in tandem with the domain – the gradual ramp-up covers both. If you’re using an email service with a shared IP pool, the IP may already have some reputation, but warming your domain is still crucial (since domain reputation has become extremely important and is separate from IP reputation). In either case, the process of controlled volume increase and engagement-focused sending remains the same. Don’t assume that a “pre-warmed” IP means you can skip domain warm-up – you still need to establish your domain’s own reputation to mailbox providers.


3. Build and Maintain High-Quality Email Lists


Your warm-up will only succeed if you’re sending to high-quality, permission-based contact lists. ISPs care deeply about recipient engagement and satisfaction; sending to bad or uninterested addresses is a recipe for spam complaints, bounces, and even spam traps – all of which can derail your sender reputation quickly. Here’s how to build and manage a quality list for your event marketing:


  • Use Opt-In Contacts Only: Ensure that everyone on your list explicitly opted in to receive your event emails (through event registrations, newsletter sign-ups, ticket purchases where they agreed to emails, etc.). Never start warming up by emailing a scraped list or contacts who never gave permission. In B2B event marketing, this might mean using lists of people who registered for past events, downloaded your whitepapers, or signed up to attend a webinar not every business card you collected. In B2C, use subscribers who signed up on your site or past ticket buyers, not a random list of attendees from a trade show. Contacts who actually want your emails will be far more likely to engage positively (opens, clicks) and far less likely to mark you as spam. If people don’t want your mail, your reputation suffers.


  • Clean Your List Regularly: Even opt-in lists degrade over time – people change jobs (their email bounces), abandon old addresses, or simply lose interest. In fact, according to research conducted by iosparkle.io email lists can decay by ~25% per year as addresses go stale. It’s critical to remove or repair invalid and inactive contacts before and during warm-up. Use email verification tools to check for addresses that are no longer valid (to avoid hard bounces). Remove any contacts that haven’t engaged in the last 6–12 months from your active send pool and move to a 're-engagement' list. This is especially important in warm-up – a high bounce rate or a spam trap hit early on can “ruin weeks of careful warm-up” with a single blow. For example, if you’re an event agency warming up a domain for a client’s mailing list, run the list through a verifier service and suppress those that come back invalid or dormant. It’s better to start with a smaller, cleaner list than a large dirty one.


  • Watch Out for Spam Traps: Spam traps are email addresses used by ISPs or anti-spam entities to catch senders with poor list hygiene. These can be old addresses that were abandoned and later turned into traps (to snag senders who don’t purge old contacts), or purely fake addresses never used by a real person. If you send to a spam trap, it’s a big red flag to mailbox providers.

    The best defense is good list hygiene: as noted, remove long-term inactive email addresses and avoid renting lists (third party data house lists often contain recycled or fake addresses that can be spam traps). If you have an older list for an event (say, attendees from 3 years ago), be very cautious – many of those emails could now be stale or repurposed as traps.


  • Implement Double Opt-In (if feasible): For some event marketers, especially in B2C, using double opt-in (where a subscriber must click a confirmation link in an email to verify their subscription) can further ensure that the addresses you have are valid and truly interested. While double opt-in may slightly slow list growth, it produces a highly engaged list, which is perfect for warming up a domain. A confirmed list means virtually no spam traps or fake sign-ups and usually more engagement. If you haven’t historically used double opt-in, consider it for new sign-ups, especially during the warm-up period.


  • Segment Out "Less Engaged" Contacts Until Later: As you warm up (as described in the previous section), you should initially exclude your least engaged or older contacts. For example, those who haven’t opened anything in a year, or cold leads from long ago, should not be in the early sends. Include them only after you’ve built up a good reputation (perhaps gradually in later weeks of warm-up or after). In practice, you might decide that during the first 4–6 weeks of warm-up, you will only email contacts who have at least opened or clicked something in the past 3 months – this aligns with Microsoft's guidance of focusing on recent engagers in early warm-up. Less engaged segments can be added in small increments once your domain/IP has demonstrated good performance.


By maintaining a high-quality list, you not only protect your sender reputation – you also increase your campaign effectiveness. The goal is to have real people who want your event information receiving your emails. This leads to more opens, clicks, and RSVPs, and fewer bounces or complaints, which in turn tells ISPs that your emails are appreciated and should be delivered reliably to the inbox.


4. Segment Your Audience for Targeted Campaigns


Effective segmentation is a powerful technique that complements both warm-up and ongoing event marketing. Segmentation means dividing your email list into smaller groups (segments) based on certain criteria – such as engagement level, demographics, past behaviour, or interests – and then tailoring your messaging and sending strategy to each group. For warming up a domain/IP, segmentation allows you to send to the most responsive subsets first and gradually include others (as discussed). For long-term success, segmentation ensures recipients get content relevant to them, which keeps engagement high. Here’s how to apply segmentation for event marketing:


  • Segment by Engagement: One of the most important warm-up strategies is to segment contacts by how engaged they are (recent newsletter signups, email opens, clicks, etc.). As noted, start with the highly engaged segment. You might label segments like “Engaged in last 30 days,” “Engaged 30–90 days,” “No engagement >90 days.” Our recommendation would be to set these segments up as dynamic lists so that contacts can flow between each segment as they meet different criteria's. This segmentation by engagement ensures you “send to subscribers who are the least likely to complain and bounce” early in the warm-up. It’s a living strategy – even after warm-up, you may continue to treat highly engaged contacts differently (e.g., emailing them more frequently, or giving them early access invites to events, because their strong engagement supports your reputation).


  • Segment by Audience Type or Profile: For event marketers, your list may include different types of people – and segmenting by these differences can improve relevancy. For example, a big corporate conference might attract prospects (sponsors, exhibitors, delegates (payers), delegates (free), speakers), customers, and partners, or new business, retain, win-back (lapsed customers) – each might get a slightly different email tailored to their perspective (different content or emphasis). Or if you run consumer events, you might segment by interest or demographics – e.g., people interested in sports events vs. music events, or families vs. single attendees. By doing so, you tailor your content and improve relevancy for each group. This relevancy boosts engagement because people are getting emails that align with their interests. Higher engagement (opens, clicks) feeds back into better sender reputation.


  • Segment by B2B vs B2C Characteristics: If your event marketing spans both B2B and B2C, you might even segment campaigns accordingly. B2B segments could be grouped by industry or job role (e.g., you might send a different style of invite to C-level executives vs. middle management professionals, highlighting different value propositions of your event). B2C segments could be grouped by behaviour (e.g., “early bird ticket buyers” vs “last-minute shoppers”) or by location (if you do multi-city events, people respond best to events in their region). In practice, an agency promoting a tech conference (B2B) might segment the list into IT managers, developers, and vendors – each gets tailored messaging about why the event matters to them, which likely increases their engagement with the emails. A music festival promoter (B2C) might segment by genre preference – sending rock concert announcements to rock fans, EDM event emails to electronic music fans, etc, or for a food festival you could segment by food types, dietary styles the list goes on! The more relevant the email, the better the engagement and the healthier your ongoing domain reputation.


  • Technical Segmentation for Warm-up: Some sophisticated senders even segment by ISP or domain during warm-up. For example, you might separate Gmail users, Yahoo users, corporate domains, etc., to monitor and manage each more closely. If you see one segment (say, corporate domains) having higher bounce or lower open rates, you could adjust strategy for that segment (maybe send even smaller volumes to them or reach out in a different way initially). However, this level of segmentation is an advanced tactic – the key principle is to send to homogeneous groups where you can gauge engagement, and ensure each group’s experience is positive before expanding.

One of the biggest email challenges I've faced during my career so far was when I was the Head of Marketing for a UK-based health technology event targeting the NHS. With 95% of our visitor prospect pool using @nhs.net email addresses, we had to work closely with the NHS technical team to get our email domain approved as a safe sender. It took weeks—if not months—of coordination, but the end result was worth it: our emails landed in inboxes, not junk folders, enabling us to deliver relevant, timely messages. We used HubSpot to drip-feed campaigns based on a matrix of 'engagement tier' and 'profile segment'—for example, IT Innovators at Tier 1, Tier 2, or Tier 3 levels—and layered in a tool called Seventh Sense to optimise send times for each recipient based on their previous open and click behaviour.

In summary, segmentation helps you send the right content to the right people at the right time, which is invaluable for both warm-up and beyond. It prevents the “one-size-fits-all” batch-and-blast that often leads to lower engagement and more complaints.


As OneSignal recommends, by dividing your list into meaningful segments (by engagement, past interactions, demographics, etc.), you can increase relevancy and thereby boost deliverability. Plus, when you do roll out the big event announcement to your whole database, you can still use segmentation to stagger the sends (sending to one segment at a time) to avoid a giant spike – effectively a controlled warm-up within your campaign execution.


5. Leverage Automated Workflows and Drip Campaigns


Manually sending individual batches of emails during a warm-up can be tedious and prone to inconsistency. This is where modern email marketing tools shine: automated workflows and drip campaigns allow you to schedule and throttle your emails in a controlled manner, and nurture your audience over time. Event marketers should use these tools to their advantage both for warming up and for engaging attendees or prospects with relevant content streams. Here’s how:


  • Use Marketing Automation Platforms: Platform-agnostic speaking, many email marketing and marketing automation platforms (e.g., Mailchimp, HubSpot, Marketo, Sendinblue, ActiveCampaign, etc.) provide features to create automated email sequences (drip campaigns) and to schedule emails or send them based on triggers. For instance, you can set up a “welcome series” workflow: when someone signs up for event updates, the system automatically sends a sequence – perhaps a welcome email, then a follow-up with event highlights, then a discount offer – spaced out over days or weeks. You can design these workflows to gradually ramp volume. During warm-up, you might intentionally stagger emails via automation. For example, instead of blasting 5,000 emails at once, create a workflow that sends 500 emails per hour over 10 hours. This kind of throttling can often be configured in dedicated sending tools or by scripting send times. The idea is to automate the consistency we discussed: let the system do the sending on a set timetable so you don’t accidentally send too much at once or forget to send on schedule.


  • Drip Campaigns for Event Engagement:

    Drip campaigns aren’t just for warm-up – they’re ideal for event marketing nurturing. Say a prospect downloads your event brochure – you can put them on a drip campaign that first thanks them, then a week later sends a testimonial from a past attendee, then later a discount code to encourage registration. These automated touches keep the audience warm and engaged leading up to the event. From a deliverability perspective, drip campaigns mean smaller, more frequent email sends rather than one-off large blasts, which can help maintain steady engagement and avoid sudden volume spikes. If you’re warming a domain, you can incorporate your warm-up into these drips. For example, in week 1 of warm-up, your drip might only trigger to 100 people per day (even if more sign up, queue them for later), then increase that cap over time. Many best-in-class tools have settings or warm-up utilities to help manage this.


  • Behaviour Triggers and Personalisation: Automation also allows behaviour-based triggers that can improve engagement. For example, if someone clicks on your “Learn more about VIP tickets” link, you can automatically send them a follow-up email about VIP packages. Or if someone doesn’t open the first invite, you can automate a re-send or a nudge a week later. These targeted follow-ups are usually lower volume and highly relevant, which is good for deliverability. For a B2B webinar event, an automated workflow might send a reminder to only those who registered but haven’t logged in by event day, which again is targeted and useful (likely to be opened rather than ignored).


  • Example of Automation in Warm-up: Suppose you’re an event agency with a new domain and you have 10,000 contacts to eventually email. Instead of manually sending batches, you use a marketing automation tool to set up a scheduled campaign: it sends 500 emails each weekday at 10am, automatically pulling in the next batch of contacts each day. Over 4 weeks, it will cover your whole list but in a slow drip. Meanwhile, the platform can automatically drop anyone who bounces or unsubscribes from subsequent sends. This hands-free approach ensures you don’t accidentally go too fast. Similarly, an independent promoter could use a tool like MailerLite or Drip to set up an automated sequence for new subscribers (perhaps garnered from Facebook ads for an upcoming event). Those new sign-ups get a pre-event content series (one email every few days introducing the event performers or speakers), which both markets the event and incidentally acts to warm up the domain with gradually increasing mail as more people subscribe.


  • Choose the Right Tools:

    The question asks for best-in-class tools, so some reputable options for workflows and drip campaigns include:

    • HubSpot or Marketo (robust for B2B and complex automations, with features to manage send frequency),

    • Mailchimp or Campaign Monitor (popular and user-friendly for both B2B and B2C, with automation and segmenting capabilities),

    • ActiveCampaign or Klaviyo (known for powerful automation and personalisation, widely used in B2C ecommerce but also useful for event drip campaigns),

    • Sendinblue (Brevo) (offers automation workflows and has a built-in warm-up feature for new senders),

    • Salesforce Marketing Cloud or Pardot (enterprise solutions often used by large event organisers for integrated campaigns).For deliverability-focused sending, some senders use services like SendGrid, Mailgun, or Amazon SES paired with third-party warm-up tools – these give fine-grained control over sending rates and are beloved by developers. Since we’re platform-agnostic, choose a tool that fits your scale and skill level, but ensure it supports the automation you need.


Remember, automation is there to help you execute the warm-up plan and ongoing campaigns correctly. It can enforce sending limits, maintain schedules, and trigger emails based on user actions – all of which contribute to better deliverability when done right. Just be sure to monitor these workflows; don’t “set and forget” entirely. Check that the automated sends are achieving the expected engagement and adjust if necessary.


6. Monitor Your Sender Reputation and Engagement Metrics


Warming up a domain/IP and running event email campaigns isn’t a one-and-done task – you need to continually monitor your performance and sender reputation, especially during the warm-up phase. By keeping an eye on key metrics, you can catch deliverability issues early and adjust your strategy. Here’s what to monitor and how:


  • Track Engagement Metrics (Opens, Clicks, Replies):

    Engagement is the lifeblood of sender reputation. High open and click rates are positive indicators; low engagement or quick deletions can be negative. During warm-up, track the open and click-through rate of each batch you send. If you expected, say, ~30% opens from your highly engaged segment and you only got 10%, investigate why. Did many go to spam? Is your content or subject line underperforming? As Litmus suggests, after each send, “check email performance like a hawk”, and ensure opens/clicks are in line with expectations. If engagement dips, consider narrowing your next send to an even more engaged subset or pausing to troubleshoot. Positive engagement (especially replies, if you encourage them in something like a confirmation email or inquiry) can significantly boost your standing with providers.


  • Monitor Bounce Rates: 

    Pay attention to bounce notifications. Hard bounces (invalid addresses) should be removed immediately from your list – too many hard bounces hurt your reputation. If you see a spike in bounces from a particular domain (e.g., a bunch of addresses at one company bounce), that might indicate a firewall or filter issue on that corporate domain. Soft bounces (like “mailbox full” or temporary blocks) should also be watched. For example, if you get a lot of “421” deferrals from Microsoft or Yahoo during warm-up, it can be normal (they’re testing your sending) – these providers often temporarily delay large amounts of mail from new senders. Microsoft’s guidance notes that delays (421 bounces that eventually either deliver or turn into 5XX errors after retry) can happen early on; as long as they eventually get delivered, it’s okay. But if you see outright blocks (5XX errors saying your sending is denied) from any ISP, take that seriously – it means you likely need to slow down or improve list quality for that ISP.


  • Keep an Eye on Spam Complaints:

    Most email platforms will report how many recipients marked your email as spam (“complaint rate”). ISPs like Gmail and Yahoo provide feedback loops via some email service providers or tools if users hit the “Report Spam” button. A high complaint rate (even >0.1% of your sends) is a red flag. If you see any complaints during warm-up, analyse who complained – were they an old contact? Did the content or frequency annoy them? High complaints could mean you need to further segment or prune the list. Remember, spam complaints are extremely damaging to sender reputationlearn.microsoft.comlearn.microsoft.com – a few angry recipients can undo a lot of warm-up work. This ties back to sending to people who expect your emails and setting up preference centres (more on that soon).


  • Use Specialised Tools for Reputation Monitoring: 

    There are great tools out there to monitor your sender reputation and deliverability health:

    • Google Postmaster Tools (for Gmail): Google offers this free dashboard for senders to see their domain and IP reputation as judged by Gmail, along with data on Gmail delivery errors, spam complaint rates, etc. If you send a decent volume to Gmail addresses, set up Postmaster Tools (you’ll need to verify domain ownership). It will show you if Gmail considers your domain/IP “High”, “Medium”, “Low” or “Bad” reputation. It’s invaluable for spotting issues with Gmail deliverysendgrid.com.


    • Microsoft SNDS (Smart Network Data Services): This is Microsoft’s version (covering Outlook.com, Hotmail, Office 365 consumer). SNDS can show you if your IPs are seeing spam traps at Microsoft, your complaint rates, and whether you’re on their internal blocklists. Since many corporate emails are served through Microsoft 365, this is useful for B2B senders too.


    • Third-Party Monitoring Tools: Services like Validity’s Sender Score (Return Path) provide a score for your IP’s reputation (0–100 scale) by aggregating data. While not used directly by all ISPs, it’s a good benchmark. Other tools can check if you’re on common blacklists (e.g., MXToolbox has a blacklist scan). There are also deliverability platforms like 250ok/Everest, Inbox Monitor, GlockApps, and MailMonitor that offer inbox placement tests and reputation dashboards. For example, GlockApps can send test emails to various seed accounts and tell you if they landed in spam or inbox on major providers, and monitor blacklist/status over time.

    • Feedback from ESPs: Some email service providers have internal warning systems – e.g., they might alert you if your bounce or complaint rate is too high. Heed these warnings.


  • Set Up Alerts or Regular Checks:

    Especially during the initial warm-up weeks, review your metrics after each send or at least weekly. It may help to set thresholds – for instance, “If open rate drops below X or bounce rate goes above Y, investigate immediately.” Many tools allow automated alerts (e.g., an alert if a campaign’s spam complaint rate exceeds 0.2%). For event marketers wearing many hats, it’s easy to be busy with event logistics and miss an email issue – so having those alerts ensures you can respond quickly.


  • Analyse by ISP:

    As hinted earlier, check if one ISP is lagging. You might notice your overall open rate is fine, but when broken down, Gmail is 5% while others are 20%. That could indicate Gmail placed you in the Promotions tab (which might be okay) or worse, the spam folder. For example, if you see “domain reputation: Bad” in Google Postmaster or a sudden drop in Gmail engagement, focus on fixing Gmail delivery (perhaps send to fewer Gmail addresses until reputation improves, or make sure your content isn’t triggering spam filters). Similarly, if a lot of B2B corporate domains bounce or don’t respond, maybe those companies have stricter filters – you might reach out individually or use text-only emails initially to appear less “marketing-like.”


  • Adjust Strategy Based on Data:

    Monitoring is only as good as the actions you take. If you find, say, a high bounce rate due to an old segment of your list, pause sending to that segment and scrub it again. If you discover spam complaints came mostly from a subset of recipients (maybe those who didn’t realis e they had signed up), consider sending a one-time confirmation or removing them entirely. If an ISP is throttling you, possibly slow your sending speed to that ISP (some ESPs let you set delivery rates per domain). On the positive side, if you see excellent engagement from a particular segment, you might accelerate sending to that group a bit (still within a controlled range) because they’re clearly boosting your reputation.


In essence, think of sender reputation as your email sender “credit score.” You need to monitor it and maintain it. As one expert puts it, email reputation controls access to the inbox – bad reputation = spam folder, good reputation = inbox. By keeping an eye on the factors that influence that score (complaints, bounces, traps, engagement, etc.), you can keep your warm-up and ongoing campaigns on track.


Monitoring isn’t a onetime task – even after you’ve successfully warmed up the domain, continue to watch these metrics for every event campaign you send. If you notice a negative trend (like engagement gradually dropping or more spam folder placements), treat it as an alarm to revisit your list quality, content, or sending practices before it becomes a serious deliverability issue.


7. Implement an Email Preference Centre for Subscribers


An email preference centre is a webpage or form where your subscribers can manage their email subscription options – such as choosing email frequency, selecting topics of interest, or opting out of certain types of emails. Setting up a preference centre is a smart, subscriber-friendly strategy that can directly benefit your email deliverability and event marketing results. Here’s why and how:


  • Give Subscribers Control: By offering options like “email frequency” or “content categories,” you empower your audience to tailor what they receive. For example, a corporate event marketer could let subscribers choose whether they want monthly updates, or only major announcements, or perhaps select which event series they care about (conferences vs. webinars vs. workshops). A concert promoter might let fans select the genres or venues they’re interested in, instead of blasting every concert to everyone. This customisation keeps subscribers happy and engaged. If someone is getting too many emails, instead of hitting “Spam” or unsubscribing outright, a preference centre could allow them to opt down – e.g. switch from weekly emails to monthly. Happier subscribers = fewer complaints and unsubscribes, which helps your sender reputation.


  • Reduce Unsubscribes and Spam Complaints: One key benefit of a preference centre is the ability for users to “opt-down” rather than opt-out completely. Maybe a potential attendee is interested in your events but doesn’t want so many emails – if they can say “only send me essential event announcements,” they’re less likely to get annoyed and mark you as spam. According to industry insight, by giving such options, businesses can reduce the overall number of unsubscribes and retain more of their list. Lower unsubscribe rates mean your list stays robust, and importantly, it means those people didn’t resort to hitting the spam button.


  • Improve Engagement Through Relevancy: When subscribers self-select what content they want, they naturally engage more with what you send. If someone opts in only to “Trade Show News” or “Music Events in Chicago,” then when you email that segment about exactly those topics, they’ll likely open and click. Preference centres thus lead to higher engagement (opens, clicks) because recipients receive content tailored to their preferences. As we’ve emphasised, engagement is a positive signal for ISPs. If your overall engagement goes up thanks to a well-implemented preference centre, you’re improving your deliverability prospects.


  • Ensure Compliance and Build Trust: Preference centres also help with legal compliance (GDPR, CAN-SPAM, etc.) by clearly honoring user choices and making it easy to unsubscribe or modify preferences. While compliance is a topic of its own, from a deliverability standpoint, making it easy and transparent for users to opt out if they want (and to not get emails they didn’t sign up for) keeps you in good standing with users and regulators. It’s far better someone unsubscribes than reports you as spam due to frustration. Many preference centres include a simple “Unsubscribe from all” as well, which you should always have (and is legally required in many jurisdictions). But providing alternatives (like “pause emails for 30 days” or “send me fewer emails”) can catch people before they go nuclear on the unsubscribe.


  • How to Set Up and Use a Preference Centre: Most email marketing platforms allow you to create a basic preference centre. You’ll typically include a link in your email footers like “Manage preferences.” On the page, consider including options such as:

    • Email Frequency: e.g., “Send me: [ ] All Updates, [ ] Only Major Announcements, [ ] A Monthly Digest.”

    • Content Categories: e.g., “[ ] Networking Events, [ ] Training Webinars, [ ] Annual Conference, [ ] Partner Offers” – whatever makes sense for your events.

    • Profile Info: maybe let them update name, company, interests, etc., which helps your segmentation efforts.

    • Temporal Pause: Some advanced centres allow “Snooze emails for X days” or similar.

    • Always have an easy “Unsubscribe from all emails” option as a safety valve.


    When a user submits their preferences, ensure your email sending system updates their segments accordingly. For instance, if someone opts out of “webinar” emails, mark them so they’re excluded from those sends. Also, make sure these changes are honored immediately (no further webinar blasts to that person).


  • Preference Centres in Action – Example: Imagine you’re promoting a large expo that includes various event types: keynotes, training sessions, entertainment, etc. Your preference centre might let attendees choose what they want to hear about: “Business Sessions, Technical Workshops, Social Events, Sponsor Offers.” A busy executive might only tick “Keynotes and Networking Invitations.” Your system then ensures they only get those specific emails – they won’t get every little update. As a result, they remain subscribed and happy to get the high-level emails, rather than unsubscribing or ignoring all your communications In a B2C scenario, say you run events ranging from food festivals to concerts to art fairs. A subscriber could opt in to just “Live Music Events” and “Food & Wine Events” and opt out of the rest. Next time you send a campaign about a gallery opening (art fair), that person won’t get an irrelevant email. They only get what they wanted, which likely means they’ll read what they get. This selective targeting via preferences augments your segmentation efforts by incorporating the user’s own input.


Overall, setting up an email preference centre is a best practice that boosts subscriber satisfaction and can indirectly boost deliverability. By sending emails that subscribers want to receive, you improve deliverability rates and reduce the chances of emails being marked as spamsendgrid.com. It’s a win-win: your audience feels respected and in control, and you get to keep a healthier, more engaged list for your event marketing initiatives.


8. Steer Clear of Spam Traps, Blacklists, and Other Deliverability Pitfalls


Even with all the right strategies above, it’s important to proactively avoid the common pitfalls that can sabotage your sender reputation: spam traps, blacklists, and spam-filter triggers. We’ve touched on some of these, but let’s summarise key ways to stay out of trouble:


  • Avoid Spam Traps by Practicing Good List Hygiene As discussed in the list management section, spam traps are a major threat. To reiterate the crucial points: never buy or rent email lists (they often contain traps), purge inactive addresses regularly, and use email verification services especially for old lists. If you suddenly start emailing a bunch of addresses that haven’t heard from you in years, that’s risky – some might now be recycled spam traps. One spam trap hit can severely damage your sending reputation, especially during the early warm-up phase when you have no “cushion” of positive history. It’s far better to have a smaller, cleaner list than a huge dirty one. Quality over quantity is the rule. Also, monitor your bounce logs; a pattern like “user does not exist” bounces could hint you’ve hit a spam trap network (some spam trap addresses bounce with such messages). In summary: send only to recipients who have recently engaged or subscribed, and you’ll greatly reduce trap risk.

  • Check and Monitor Blacklists: Email blacklists (or blocklists) are databases that track IPs or domains sending spam. Ending up on a major blacklist (like Spamhaus, Barracuda, etc.) can cause broad delivery issues. During warm-up, you shouldn’t hit any blacklist if you’re following all the best practices – but it’s wise to monitor. Use tools like MXToolbox or a blacklist monitoring service to see if your sending IP or domain gets listed. Many ESPs also alert you if a blacklist listing occurs. If you do get blacklisted, you need to diagnose why (often it’s because of spam trap hits or high complaints) and then follow the blacklist’s procedures to request delisting once you’ve fixed the issue. For example, Spamhaus has a form to fill out and will expect you to have cleaned your list or resolved whatever caused the listing. Avoiding blacklists in the first place is ideal: stick to opt-in contacts, don’t send emails that look spammy (more on content next), and respect sending limits. Keep an eye on your sender reputation scores (as mentioned, Sender Score, etc.) because a plummeting score could precede a blacklist listing.

  • Be Mindful of Spam Filter Triggers (Content and Technical): Spam filtering is complex and varies by provider, but some common red flags can be avoided:

    • Content Red Flags: Especially in your early warm-up emails, avoid overly “spammy” content. This means don’t use all caps or excessive exclamation marks in subject lines, don’t use phrases like “FREE $$$!!!” or other classic spammer tropes. The SparkPost warm-up guide emphasises keeping content “natural” and not overly salesy during warm-up. While modern spam filters are more sophisticated than just a simple keyword check, blatant spammy language can still hurt. For event marketers, this usually isn’t a big issue if you’re writing genuine event info, but be cautious with things like using “Free” too many times or weird formatting. Also, ensure your plain-text version (if you send HTML emails) is present and matches, and that your email isn’t just one big image (that can trigger filters).

    • Technical Red Flags: Apart from authentication (SPF/DKIM) which you’ve set up, other technical factors include having a proper unsubscribe link in every email (missing unsubscribe is a huge no-no and can get you spam-foldered or worse, in violation of laws), and properly formatting your email headers. If you’re using a reputable ESP, they handle most of this. Just don’t do things like embed forms or scripts in email – stick to standard email best practices.

    • Sending Domain and IP Consistency: Always send from a consistent domain. Don’t alternate between many new domains – pick one and build its reputation. If you use multiple sending IPs, ensure they have similar good behaviour. Randomly popping up on different IPs/domains without warm-up each time looks suspicious (spammers often “snowshoe” across many IPs). Stick to the program – warm one domain/IP setup at a time, or if you must add another, warm it too.

  • Maintain a Stable Sending Cadence: We’ve mentioned this, but it’s worth noting as a pitfall: large spikes in volume or erratic sending patterns can trigger ISP alarms. If you’ve warmed up and then you go dormant for months, you might need a mini warm-up when you come back. Try to maintain some baseline of activity on your domain. For example, even between big events, maybe send a monthly newsletter to keep things warm. If you can’t send regularly, be extra careful when restarting after a long pause (treat it somewhat like a warm-up again, starting with smaller sends). ISPs have memory, but if they haven’t seen you in 6 months, they might treat your new big blast as suspect.

  • Use Testing Tools for Content and Spam Scoring: Consider using tools like Litmus or Email on Acid to test your emails before sending to the full list. These tools can run your email through spam filters and give you a report of any issues (like if your IP is on a blacklist, or if your content tripped something). They often also show how your email renders, but in context here, the spam testing is useful. Some offer a spam score (like SpamAssassin score) – if it’s high, tweak your email to lower it. This pre-flight check can catch problems before you send to thousands of contacts.

  • Stay Compliant and Ethical: Finally, adhere to email marketing laws (CAN-SPAM, CASL, GDPR depending on your audience). Always include a clear unsubscribe link, your physical mailing address (for CAN-SPAM compliance), and honor all opt-outs immediately. Not only is this legal compliance, but ISPs monitor things like spam trap hits which can include “honey pot” unsubscribe links to test if you honor removals. Being a responsible sender goes a long way in establishing a good reputation.

By avoiding these pitfalls, you maximise the chances that your carefully warmed-up domain/IP will continue to deliver great results. Think of it like maintaining good health after getting in shape: you did the hard work to build a good sender reputation; now keep it clean. Keep your lists fresh, sending practices solid, and stay informed about deliverability trends (ISP rule changes, new spam filters, etc. – for example, in 2024 Gmail made some new bulk sender requirements, so staying updated via industry blogs is wise). If you do hit a snag like a blacklist, don’t panic – pause and troubleshoot systematically, and you’ll usually recover.

Conclusion:

Warming up a new email domain or IP address is a critical process that every event marketer should undertake with patience and diligence. By following the steps outlined – from proper technical setup with SPF/DKIM/DMARC, to gradually ramping up send volumes, focusing on list quality, smart segmentation, leveraging automation, monitoring results, empowering subscribers with preferences, and avoiding known pitfalls – you build a solid sender reputation that enables your event campaigns to reach their audience.


The reward for this work is higher deliverability: your corporate conference invites land in prospects’ inboxes (not junk), your trade show newsletters reach partners reliably, and your concert announcements get seen by eager fans. In the competitive inbox environment of 2025, where ISPs employ sophisticated algorithms to scrutinise senders, domain and IP warm-up isn’t optional – it’s a fundamental prerequisite for email success. The good news is that with a well-planned approach and the right tools, you can successfully warm up and enjoy excellent open rates and engagement for your event marketing emails.


Stay consistent, stay vigilant with your data, and you’ll set the stage for email marketing success – filling your events with attendees who received your message loud and clear (in their inbox).


Bonus: Email Domain/IP Warm-Up Checklist (Free, Ungated Download!)


Warming up your email domain or IP address takes time, consistency, and attention to detail—but it doesn’t have to be overwhelming. To make it easier, we’ve created a free downloadable checklist specifically for event marketers.


This practical, step-by-step guide covers everything from:

  • DNS setup (SPF, DKIM, DMARC)

  • Choosing the right subdomain strategy

  • A week-by-week warm-up schedule

  • Segmentation and list hygiene steps

  • Preference centre essentials

  • Deliverability monitoring tools


Use it to stay on track, delegate tasks across your team, or validate your warm-up strategy before launch.Whether you're preparing for a major B2B conference or a B2C festival, this checklist helps you get inbox-ready with confidence.




Need help planning your warm-up strategy or reviewing your email setup? Book a free 30-minute consultation with our team to get expert, tailored advice for your event marketing campaigns.
Need help planning your warm-up strategy or reviewing your email setup? Book a free 30-minute consultation with our team to get expert, tailored advice for your event marketing campaigns.

Glossary of Email Deliverability Terms


  • SPF (Sender Policy Framework): A type of DNS record that tells mailbox providers which mail servers are authorised to send emails on behalf of your domain. It helps prevent spammers from sending fake emails using your domain (email spoofing).

  • DKIM (DomainKeys Identified Mail): A security protocol that adds a digital signature to your emails. This proves that the message wasn’t tampered with in transit and confirms it came from your domain. Requires a public key to be added to your DNS records.

  • DMARC (Domain-based Message Authentication, Reporting and Conformance): A policy framework that builds on SPF and DKIM. It tells mailbox providers what to do if an email fails authentication (e.g., reject it or send it to spam) and allows you to receive reports on email authentication results.

  • Spam Trap: An email address used by mailbox providers or anti-spam organisations to catch senders with poor list hygiene. If you send to a spam trap, it signals you're emailing without proper consent or list cleaning, which harms your sender reputation.

  • Hard Bounce: An email that is permanently undeliverable—typically because the address doesn’t exist. These should be removed from your list immediately to avoid damaging your reputation.

  • Soft Bounce: A temporarily undeliverable email—common reasons include full inboxes or server issues. These can sometimes be retried, but if they persist, the address should be removed or suppressed.

    1. Complaint Rate: The percentage of recipients who mark your email as spam. Even a rate above 0.1% can hurt your deliverability. High complaint rates indicate poor targeting or irrelevant content.

  • Engagement Tier: A way to categorise contacts based on their recent interactions with your emails. For example:

    • Tier 1: Opens and clicks in the last 30 days

    • Tier 2: Opens in the last 90 days

    • Tier 3: No engagement in the last 90+ days

    Using engagement tiers helps prioritise your most responsive contacts during warm-up and beyond.



Research Links Used to Inform This Article:


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