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Warming Up Your Custom Sending Domain in SmartrMail
Warming Up Your Custom Sending Domain in SmartrMail

Learn how to warm up your new custom sending domain.

Jack avatar
Written by Jack
Updated over a week ago


When switching to a new sending domain in SmartrMail, it's vital to establish a strong sender reputation. This process, known as 'warming up' your domain, involves gradually increasing your email volume while generating positive engagement indicators that your emails are valued by your subscribers in the eyes of inbox providers. The key is to foster more opens and clicks relative to unsubscribes, complaints, and spam reports. It's more about the engagement ratio than just the volume.

Why Warm Up Your Sending Domain?

  • Builds Trust with Email Providers: Gradually increasing your email volume helps establish trust with email service providers, reducing the risk of your emails being marked as spam.

  • Enhances Email Deliverability: A good sender reputation boosts the likelihood of your emails landing in the inbox, not the spam folder.

  • Improves Engagement Rates: Sending to engaged subscribers increases the chances of your emails being opened and clicked, which positively impacts your sender reputation.

Step-by-Step Guide to Warming Up Your Domain

  1. Identify Engaged Subscribers

    • In SmartrMail, use our segment tools to create a list of subscribers who frequently open and interact with your emails. If you have never sent with SmartrMail, create this segment in your previous ESP and import it into SmartrMail as a separate list.

    • We recommend using the rules Has opened any emails in (# Days) along with Has clicked any emails in (# Days) and if you really want to fine tune your engaged subscribers add the rule Has ordered in (# Days)

  2. Start with Your Most Engaged Subscribers

    • Send your first email campaigns to this engaged segment.

  3. Monitor Engagement and Deliverability

    • Each week, slowly increase the number of recipients you send emails to, expanding your reach within your engaged subscriber base.

  4. Gradual Increase Based on Performance:

    • For the first two campaigns, target the most engaged subscribers. If you achieve an open rate higher than 30%, click rate above 1%, and a complaint rate below 0.02%, then start sending to your entire list.

  5. Ongoing Monitoring and Adjustments:

    • After completing the warm-up process, if your campaigns fall below a 10% open rate, revert to sending to your most engaged segment. Persistent low engagement may require cleaning your list of unengaged subscribers.

  6. Reach Full Volume Gradually

    • The warm-up process typically spans several weeks. By the end of this period, you should be able to send to your full email list without negatively impacting your sender reputation.

Additional Tips

  • Maintain Consistent Sending Patterns: Regular sending schedules help establish a consistent sender reputation.

  • Keep Content High-Quality: Engaging and relevant content encourages positive interactions from your subscribers.

  • Be Responsive to Feedback: If subscribers are marking your emails as spam, review and adjust your email content and targeting.


Warming up your new sending domain is a vital step in maintaining effective email marketing campaigns. By focusing on your most engaged subscribers and gradually increasing your email volume, you can build a strong sender reputation, ensuring your emails consistently reach your audience's inboxes.

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