How to warm up a new sending domain


If you have been using ActiveCampaign and recently purchased a domain for the first time or your organization is rebranding, you must tread carefully with your new domain to avoid deliverability issues. Your domain's reputation influences deliverability, ensuring your messages reach the intended inboxes.

In this article, we'll explore the importance of domain reputation and provide valuable insights into warming up a newly purchased or newly utilized domain to establish trust with mailbox providers (MBPs).

Take Note

This guidance is intended for users starting to send email with a new domain. If you are new to ActiveCampaign, learn how to set up your deliverability in your first 30 days to get started.

We understand that warming up a domain reputation can be frustrating when your business needs to move fast. However, it’s necessary to apply these common best practices to establish a solid reputation for your new sending domain and achieve optimal deliverability.

Understanding Domain Reputation

Domain reputation is a measure of your domain's trustworthiness in the eyes of mailbox providers (MBPs) like Gmail, Yahoo, and Microsoft Outlook/Office 365. A positive reputation increases the chances that your emails will be delivered to recipients' inboxes instead of being marked as spam or sent to the spam folder.

Factors influencing domain reputation include email engagement, spam complaint rates, spam traps, bounce rates, your sending history, and even the age of the domain, which is why it's important to think about domain reputation with a new domain.

For a deep dive into domain reputation, see Email Sending Reputation: How does Domain Reputation work?

Our friends at Postmark also have a good article on Domain reputation, explained.

Extreme Caution! The First 24-48 Hours

If you've owned a domain for a while and have yet to use it but want to start sending emails, you can skip this section and go to the next. This guidance is for users starting to send emails with a new domain.

Upon purchasing a new domain, exercising patience is important. Using the domain for email communication immediately after acquisition may send warning signs to MBPs like Gmail and Yahoo, as this behavior is often associated with suspicious or malicious activity.

Some blocklists may automatically block your domain if they see you sending emails in the first 24 hours after the domain was registered. It's best practice to completely refrain from sending any emails for the first 24-48 hours to avoid triggering spam filters.


Before sending any emails, we recommend that you set up DKIM before sending any messages. DKIM helps verify the authenticity of your emails, enhancing your domain's credibility in the eyes of MBPs. This is free on all plan levels.

Learn how to set up DKIM with ActiveCampaign.

Start Sending

The only way to warm up your new domain is to start sending emails. But it’s important to do this right. Here are our best practices to slowly warm up the domain and establish a solid reputation:

Gradually Increase Volume

Begin with a low volume of emails and gradually increase the sending volume. Avoid any sudden, large spikes in sending volume at all costs.

There is no perfect number as to what you can or should send per day. Ideally, you should send less than a thousand messages daily for the first few days, and then you can gradually start increasing.

Below is an example of how a business could gradually increase its sending volume. Note that these numbers are not fixed and vary based on many factors. Including but not limited to how contacts respond to these communications and your list size.

  • Day 1: < 500 emails
  • Day 2: < 1,000 emails
  • Day 3-7 < 5,000: emails
  • Day 7-14: < 20,000 emails
  • Day 14 - 21: < 50,000 emails
  • Day 21 - 30: < 100,000 emails

If you don’t have a large list, you only need to worry about the first week or so. This gradual approach helps avoid sudden spikes that might be perceived as spammy behavior.

Send to your most engaged recipients

When you start warming up your domain, target your most engaged contacts. These individuals are more likely to interact positively with your emails, signaling to MBPs that your content is relevant and desired. Make sure to avoid sending to any lists that are older and less engaged. These unengaged lists can hurt your new domain’s reputation.

ActiveCampaign offers various tools for identifying engaged contacts on your subscriber list(s):

Brand Association

If MBPs can associate your new domain with your pre-existing brand, they will trust it more. Include recognizable brand elements in your emails, such as logos and consistent messaging, to reinforce that your brand is legitimate. Try to use the same email templates you were using with your old domain. In addition, your domain should redirect to your website like other domains your business uses.

Transparent WHOIS Records

WHOIS is a widely used internet record listing that shows who owns a domain and how to contact them. It is important to ensure your domain's WHOIS records are as clear and transparent as possible by confirming you do not have any WHOIS masking or Private Domain Registration through your domain provider.

For more information on this see #2 under “With distrust comes limited use” from our friends at Spamhaus.

This information helps build trust with MBPs, showing that your domain is associated with a legitimate and accountable business. If your domain’s WHOIS records match the contact information on your website that makes it much easier for MBPs to identify and trust the new domain.

Learn more about what WHOIS is and how it works.

Tread Carefully with Unusual Top-Level Domains (TLDs)

In a URL, the top-level domain (TLD) is after the first dot in the domain name. For example, .com, .net, and .org are the most popular TLDs.

Avoid using uncommon TLDs, such as .club, .live, or .market. These are viewed with suspicion by both MBPs and recipients and are likely to have major deliverability issues. Stick to more conventional TLDs like .com to avoid unnecessary scrutiny. These are typically more expensive domains to buy, but they provide better deliverability.

Exercise Patience Before High-Volume Campaigns

Resist the urge to launch high-volume marketing campaigns immediately. Waiting at least 30 days of slowly increasing your sending volume allows your domain to establish a solid sending reputation.

Monitor with Google Postmaster Tools

If you have time, we recommend using Google Postmaster Tools to monitor your domain's sending reputation.

Google Postmaster Tools is a free tool that shows you how your domain reputation is doing in the eyes of the world's largest MBP, Gmail. Gmail will tell you if your domain reputation is Red, Yellow, or Green. This can give you the confidence to increase the sending volume or to stop sending altogether.

Learn how to set up and use Google Postmaster Tools.

Additional Resources

Our friends at Postmark also have a guide on warming up domains from a transactional email view.

Spamhaus also has a guide on best practices for owners of a newly registered domain that we highly recommend.

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