An Ultimate Guide to Using Email Subdomains in Your Campaign

An Ultimate Guide to Using Email Subdomains in Your Campaign
11 January, 2023 • ... • 8539 views
Maria Bidogaeva
by Maria Bidogaeva

An email subdomain is a simple yet efficient way to increase the reputation and deliverability rate of your emails. In this article, you’ll learn more about email subdomains’ benefits, examples, and steps to set them up.

What is an email subdomain?

An email subdomain is an optional division inside the root domain. Each subdomain may have its own reputation rate not impacting others or the main domain. It can also have another new IP address while staying within the same parent domain.

An email subdomain looks like a prefix that comes before the domain in an email address:

An email address with a subdomain example

Email subdomain examples from real life

You might be wondering how big corporations use email subdomains for their business success. What if we tell you that you’ve probably seen many email subdomain examples in your inbox? The following are some of the real-life email subdomains to inspire your own solutions:


[email protected]

[email protected]


[email protected]

[email protected]


[email protected]

[email protected]

[email protected]

[email protected]


[email protected]

[email protected]

[email protected]

Many big companies use email subdomains in their email addresses. But they do it differently as there are several methods you can organize your subdomains. For example, Google has separate subdomains for its services (Google Docs, Google Slides, etc.) while SoundCloud sorts subdomains according to their functions (notification, announcement, etc.). You can use any of these methods depending on your business needs.

Why use a subdomain email address?

Besides control of the sender reputation, subdomains help to track and manage email deliverability and prevent important emails from going to spam. It is a great way to regulate the emails you’re sending. Let’s look at email subdomains’ benefits one by one. 

To segment engagement levels

Marketers need their emails to successfully land in subscribers’ inboxes. But email deliverability — a key marketing metric — is complicated. It is determined by several factors, one of which is engagement. Engagement estimates how subscribers interact with campaigns. This measure combines open rate (OR), click-through rate (CTR), unsubscribe rate, and website traffic from email.

Different email types naturally get different engagement. Let’s examine two types of emails

Marketing emails include promotions, newsletters, announcements, reactivation emails, and other campaigns. They tend to have a lower open rate and engagement. 

Transactional emails, on the other hand, are brought by the user’s actions. These are password changes emails, order or subscription confirmations. Transactional emails have a high open rate and engagement as users are, in most cases, actively waiting for them. 

It’s possible to send emails of these two types alongside. In fact, it’s the default option. But emails with a worse engagement can negatively influence others. In our case, marketing emails can make the engagement and deliverability of the transactional ones lower.

Transactional emails are crucial for a good user experience. Without receiving their registration details in the first place your subscribers won’t be able to make an order at all. Marketing emails come second. To make sure your clients always get transactional emails — it’s better to have separate subdomains for transactional and marketing emails, for example. Sending different types of emails from different subdomains helps to keep the deliverability rate consistent across one type of content. If you do that, even if your promotional emails end up in spam folders, you can be sure it won’t affect the transactional ones. Subdomains are one of the solutions that secure the deliverability of important emails.

To investigate deliverability problems

As we said, deliverability is complex. And ensuring success in this area may not be straightforward.

Understanding what causes a rise or a fall in deliverability is easier with subdomains. They help to narrow the source of possible issues and find solutions faster. For example, you have different subdomains for product launches and sales. That way you can compare their deliverability rates and clearly see what types of emails or what strategies need to change. Having separate subdomains is also helpful to conduct deliverability tests and experiments.

To protect sender reputation

One of the factors that affect email deliverability most is the sender reputation. If email services like Gmail or Outlook deemed the sender trustworthy, its emails will probably avoid the spam folder. Sender reputation is largely based on the domain and IP address history. If subdomains have different IPs each subdomain has its own reputation rate. 

In case something goes wrong with one subdomain’s reputation, the others and the root one aren’t affected. Suppose, you do something wrong and your re-engagement email campaigns end up in the spam folder. If you have separate subdomains, your transactional emails won’t be affected by that and will still show up in your subscriber’s inbox.

Moreover, if one subdomain’s reputation is damaged beyond repair, one of the solutions is to simply move to another subdomain. If you only have a root domain transitioning to a different one will be a much harder task.

Essentially, subdomains help to “diversify the risks”. Many brands separate product lines to achieve the same effect. For example, Dior has a main makeup range and a separate one called Backstage. If Backstage makeup got negative reviews, the reputation of the main line won’t be affected. The same goes for email subdomains.

When to use email subdomains

Let’s break down when you should use email subdomains:

  • To separate transactional, promotional emails and informational newsletters from each other.
  • To track the analytics, such as deliverability rate, more accurately.
  • To separate emails from different teams, such as global, events, sales, and outreach teams so that they can analyze their metrics separately.

Email subdomains are beneficial to email marketing strategy no matter the business sphere. Whether you run a retail e-commerce business, provide financial services, or work in any other industry where you need to perform email testing to improve deliverability, email subdomains are a useful solution.

You now know all the benefits of subdomains but maybe you have one other question.

Can I just send messages from different names on the same domain?

Email name is what comes before “@” in your email address. For example, in Apple’s address [email protected], “news” is the name, while “insideapple” is a subdomain.

You can change the names on the same domain to make it easier for your subscribers to know who the email is from or what it’s about. However, from the email service provider’s point of view, it neither changes the IP nor the reputation. That means emails with different names would still have the same reputation. 

In this case, you might be wondering why you can’t just send different types of emails from different domains. Well, the domain reputation will be different but several domains might also confuse your contacts. If subscribers simultaneously get emails from, say, and they might think one sender isn’t legit. For these reasons, subdomains are among the best solutions to manage the deliverability rate while being subscriber-friendly.

How to set up an email with a subdomain

Want to create email subdomains for your business? We’ve got some tips for you! Here, we’ve compiled a step-by-step guide for you to set up your first email subdomain. 

Create a name for your subdomain

To ensure your email subdomain delivers proper messages and doesn’t confuse subscribers, its name should be something simple yet suitable. Depending on the main content of your messages, it can be something like “notification”, “announcement”, “reminder”, etc.

You’ll have to check the availability of the subdomain name and register it in your domain registrar similar to what you did registering the domain itself.

Set up authentication protocols for the new subdomain

How to stop emails from going to spam? Start by authenticating them. Email authentication is a process of verification that an email sender is allowed to use the domain or subdomain.

Since phishers and spammers tend to send their emails using someone else’s domains, it is essential to set up authentication protocols for new subdomains. That way your sender’s address is protected from spoofing and your letters aren’t going to spam. 

Four essential parameters for email authentication are:

  1. Sender Policy Framework (SPF)
  2. Domain Keys Identified Mail (DKIM)
  3. Domain-based Message Authentication, Reporting & Conformance (DMARC)
  4. Brand Indicators for Message Identification (BIMI

In Selzy you need to go to settings and choose “Domain authentication”. There you’ll see your added domains and their status. Domains that you don’t use will be marked as “disabled”.

A screenshot of the domain authentication settings page in Selzy

From there, click on the green “Create” button and follow the instructions.

A screenshot of the domain-adding settings in Selzy

For more detailed information, follow this guide on how to set up authentication protocols.

Warm up the subdomain

After you set up a new subdomain, don’t start sending just yet. You should warm it up first. If a new subdomain sends bulk emails right away, inbox service providers like Gmail or Outlook will find it suspicious. As a result, all the emails from the new subdomain may be marked as spam. Warming up a new subdomain is necessary to gain the inbox service providers’ trust and ensure deliverability. 

The fewer emails you send, the less suspicious it is. To manually warm up the subdomain, determine your most-engaged subscribers. Then, send them emails from the new subdomain and increase the volume slowly.

Sending out your emails gradually results in higher engagement and reputation rates. So, don’t skip this step.

Send links in your email to your root domain

To ensure your subdomain reputation, you should add links to your root domain in the emails. It will help your subscribers and email services to know that your email is legitimate.

Note that if your domain has a low reputation and you include a link to it in the email, the email may end up in the spam folder.

An email from New York Times’s subdomain with a link

Create rules for subdomain email addresses

Next step is creating rules for your subdomain. They are useful to keep track of the replies you receive in your inbox.

If you use the subdomain only to send emails, redirect it to the root domain. That way even users who type your subdomain into the address bar of their browsers will end up on your site anyway.


Email deliverability might be a tricky parameter to regulate. An email subdomain is one of the things that can help you with it.

Email subdomains are a helpful addition to your email marketing strategy success as they ease deliverability tests and adjustments and protect sender reputation. Remember to do the following when making one for your business:

  • Create a name
  • Set up authentication protocols
  • Warm it up
  • Send links to the root domain and create rules for the subdomain

Getting an email subdomain is another step to making your email marketing more effective, so make sure to give it a try.

11 January, 2023
Article by
Maria Bidogaeva
A literature and economics degree holder with a background in writing newspaper articles and educational blog posts. I first encountered digital marketing when I was launching my online language learning project. I believe digital marketing can be challenging and fun at the same time, so I hope to help others make the best of their experience with it. My hobbies include online education, learning foreign languages, and American literature.
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