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How to warm up email domain: All you need to know in 2024

Reading Time: 8 minutes

Sending marketing emails from a new domain without a domain warmup can be disastrous. 

Internet and email providers consider a sudden flurry of emails from a fresh domain suspicious. This may result in your emails going straight to the recipient’s spam folder or being blocked entirely.

The key is to gradually increase the number of emails you send over an extended period of time, usually a few weeks.

In this article, we detail email domain warming best practices. Here, you’ll learn how to warm up new email domains for better deliverability.

We’ll also provide a quick step-by-step guide on how to warm up your email domain with Omnisend.

Let’s begin!

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Email domain warm-up explained

Email domain warm-up is the process of progressively sending test emails from a freshly minted domain. This establishes a positive sender reputation before launching full-scale email campaigns. 

The key reason to warm up your email domain is to boost email deliverability. You need to earn the trust of Internet Service Providers (ISPs) and Email Service Providers (ESPs).

If you send a high volume of emails, then email domain warming is essential because ISPs frequently flag emails from new domains as suspicious. This increases the likelihood that they will wind up in spam folders. ESPs also impose stringent sending limits that restrict your ability to send emails. 

This is why failure to warm up your email domain can cause your emails to not reach their target inboxes.

Conducting email warm-ups increases your new domain’s chances of succeeding. Gradually increase daily email volumes while closely monitoring performance metrics. 

As recipients respond positively to your emails, the ISPs begin to trust your domain increases. The ESPs will gradually increase your sending limits, improving your email deliverability.

Comprehensive email domain warming is essential for establishing a good email sender reputation. In fact, it is vital for overall email marketing success. Email domain warm-up improves inbox placement, open rates, click-through rates, and conversions.

Best practices to warm up an email domain

Email domain warming is best approached as a science, not an art. This means that it is not an exercise that you freestyle, rather, it’s a well-organized process.

This includes starting with a small volume so ESPs don’t consider you a spam threat as you establish your reputation. It also includes responding promptly to feedback, and segmenting your audience appropriately to ensure everyone receives relevant, appropriate information.

That said, here are some best practices for email domain warming.

Create a warm-up strategy

Develop a well-thought-out email warmup strategy before launching an email marketing campaign from a new domain.

Consider the following when creating your email warm-up strategy:

  • Your high-performance emails: Put your best-performing emails forward. This will increase the chances of good engagement, which tells ESPs that you’re sending high-quality messages.
  • Your engaged audiences: Create an email list of recipients most likely to open and interact with your emails.
  • A timeline: Create a schedule that details how many emails you’ll send per day or week. Also, detail how you plan to increase the volume and frequency of emails over time. We recommend you send no more than one campaign per day, three times a week.

A warm-up strategy could look something like this:

WeekEmails/dayEmails/weekSegmented audience
Week 1250 emails750 emailsExisting subscribers only
Week 2500 emails1,500 emailsExisting subscribers + most active customers
Week 31,000 emails3,000 emailsExisting subscribers + all customers
Week 42,000 emails6,000 emailsExisting subscribers + customers + new signups

You can monitor your email marketing data after a few weeks and start to increase the number of emails you send.

Segment your email list

By segmenting your email list, you can optimize your domain warm-up campaigns. Using personalization and targeting to segment your list can improve your email deliverability and performance.

For instance, Omnisend’s segmentation feature involves splitting your email list into specific groups based on shared characteristics, such as:

  • Preferences
  • Geographics
  • Demographics
  • Purchase history
  • Customer behavior
  • Engagement levels
  • Active/inactive subscribers

Clean your email lists

Regularly remove inactive or invalid email addresses from your email list.

Regular email list cleaning and updating can significantly improve your email deliverability. It enables your messages to reach only engaged and interested recipients.

Use email verification or cleanup tools to identify and remove spam traps, hard bounces, and other problematic email addresses from your list.

Follow ESP limits

When following an email warming strategy, it is essential to identify the limits imposed by ESPs. You must adhere to these sending limits to avoid being marked for suspicious activity or added to the spam list.

This table shows some of the sending limits of some popular ESPs as of February 2024:

1and13,500 emails/hour
BlueHost150 emails/hour
DomainFactory500 emails/hour
DreamHost100 emails/hour
FrogHost1,000 emails/hour
Gmail500 emails/day
GoDaddy250-1000 emails/day
Google Apps500 emails/day
HostGator500 emails/hour
Hostinger200 emails/hour
Hotmail100 emails/day
InMotion250 emails/hour
Mailchimp300 emails/hour
Namecheap50-10,000 emails/hour
Office36510,000 emails/day
Outlook10,000 emails/day
PHPNet100 emails/hour
RackSpace10,000 emails/day
Yahoo!100-500 emails/hour
Zoho250-1,000 emails/day

It’s important to note that these limits are subject to change and may vary depending on the provider’s plan.

Read these additional resources to update yourself on the latest ESP limits:

Sending limits of various Email Service Providers

Lists of hosts and their email sending limits

Start with a low volume

When warming up an email domain, it’s advisable to send low-volume emails and gradually scale up. As previously mentioned, this approach helps to build a positive sender reputation. Exceeding the ESP send limits as a new domain strongly indicates ‘spam’ activity and often results in actions such as blocking, blacklisting, or spam folder rerouting.

Engaging in inconsistent email warmups can also upset the ISPs. The most effective email warming involves gradually and consistently increasing the volume of emails you send.   

In the graphs below, you can see how consistency can affect your reputation.

Best practices to warm up an email domain
Image via Omnisend

Target engaged recipients first

Target your most engaged recipients first, and then you can gradually expand your outreach in batches. Your initial send list should comprise existing customers, recent subscribers, or website visitors with high on-site activity.

Having demonstrated clear interest, this selective group will help your new domain to build a good reputation. They gain momentum through higher open rates, clickthroughs, and lower complaints.

Authenticate your email

When conducting email warming, ensure that your email domain is properly authenticated. This safeguards it against spoofing or forgery by hackers or fraudsters.

Implementing any of the three main email authentication protocols for an email domain is essential. They are SPF, DKIM, and DMARC:

  • SPF (Sender Policy Framework): allows you to specify which IP addresses are authorized to send emails from your domain.
  • DKIM (DomainKeys Identified Mail): allows you to sign your emails with an encrypted digital signature to prove legitimacy.
  • DMARC (Domain-based Message Authentication, Reporting, and Conformance): allows you to set policies for how the ESPs and ISPs should handle your emails that fail verification.

Improve IP reputation

Email domains and IP reputations are deeply linked. Your associated IP address plays a significant role in email deliverability.

IP addresses associated with your email domain come in two forms:

  • Shared IP addresses: These are used by multiple senders and are usually provided by your email service provider. They can be likened to a shared office space where multiple companies use the same office address.
  • Dedicated IP addresses: Dedicated IP addresses are single-use and are usually purchased by the sender.

Be attentive to the reputation of the IP addresses associated with your email-sending infrastructure. It’s important to improve or change it when necessary.

Avoid spam triggers

Steer clear of spam triggers in your email content during domain warmup. Spam triggers can vary depending on the ESP and ISP in question.

Be wary of spam triggers in the following:

  • Your email content:
    • Using overly promotional or exaggerated language, such as “free,” “guaranteed,” or “risk-free”
    • Excessive use of capitalization, punctuation, or symbols, such as “BUY NOW!!!,” “LIMITED TIME OFFER!!!” or “$$$”
    • Using generic or impersonal sender names, such as “noreply,” “admin,” or “support”

      Take a look at the spam content from this Gmail account.
Best practices to warm up an email domain: avoid spam triggers
Image via Gmail
  • Your email list:
    • Sending emails to unconsenting recipients
    • Sending emails to inactive or dormant email addresses
    • Sending emails to spam traps or honeypots
  • Your email frequency:
    • Sending too many emails
    • Sending inconsistent emails
    • Sending emails at irregular or inappropriate times

Craft high-quality content

Another best practice for email domain warming is to create high-quality email content. The quality of your email content determines how your recipients perceive and respond to your emails. As such, you want it to impress and convert.

To ensure a successful email domain warming, your email content should be:

  • Personalized
  • Engaging
  • Relevant
  • Clear

Here’s an example of well-crafted email content.

How to warm up an email domain
Image via Really Good Emails
Great email deliverability is our #1 priority.

Step-by-step: How to warm up email domain with Omnisend

Omnisend offers one of the most streamlined solutions to systematically warm up email domains. 

To warm up your email domain with Omnisend, follow these simple steps:

  • Prepare for warm-up: Before you begin your email warmup sequence, thoroughly declutter your email lists. Ensure your email content is of high quality as well. Implementing this strategy guarantees maximum engagement throughout the earliest stages. 
  • Get started with Omnisend: To get started, create an account with Omnisend. If you have data from a previous marketing automation platform, you can migrate it into Omnisend. This helps you retain your existing customers’ information. 
  • Segment your email list: Split your email list into small groups based on activity levels. Segment contacts into two groups: most active and engaged contacts. It’s important to note that Omnisend automatically creates different segments the moment you subscribe or connect your store to its platform.
How to warm up an email domain with Omnisend
Image via Omnisend
  • Initiate the warm-up with Omnisend: Kickstart your email warm-up with Omnisend. You can do this under the “Reports” → “Deliverability” section on your dashboard. The warmup duration could span 3-25 gradual steps, depending on your subscriber volumes.
Omnisend report - deliverability
Image via Omnisend
  • Email campaigns during warm-up: Use or create distinct content for each new warm-up batch. This helps you avoid repetitive sends because contacts may overlap across segments. Omnisend also automatically generates segments for your warm-up campaigns.
  • Monitor and fine-tune your email warmup strategy: Closely track important email marketing metrics. This includes open, clickthrough, and engagement rates to gauge ISP response. Low engagement signals slower expansion, so monitor and adjust if necessary.
Omnisend email perfomance
Image via Omnisend

Free email warmup: Tools and services

Warming up your email domain doesn’t have to come with a hefty price tag. There are a number of email warmup tools that help you gradually establish your sender reputation for free.

Here are some free email warm-up services to consider:

  • GMass
  • MailFlow
  • Omnisend
  • Woodpecker
  • QuickMail Auto Warmer

Wrap up

Warming up your email domain is essential for optimal deliverability and building a positive sender reputation.

To warm up your email domain effectively, create and follow a warm-up strategy. Start with a low volume, target engaged recipients first, and be consistent.

By following these best practices and others outlined here, you can improve your deliverability and reputation so you can have successful email marketing campaigns.

Ready to take your email marketing game to the next level?
Article by
Karolina Petraškienė

Karolina is a writer, content marketer, and email enthusiast at Omnisend. When she's not curating articles, you can find her in the woods challenging herself in hiking boots or off-roading her bike.