Everything You Need to Know About Email Subdomains

There’s no other way to put it – using subdomains is a necessary part of achieving good long term email deliverability. Though email has been around for almost 50 years, the way internet service providers (ISPs) like Gmail and Outlook monitor what emails land in inbox and what goes to spam is changing every day. What do you need to stay on top of these changes? You guessed it – email subdomains.

If you use Gmail, just check your spam folder. There’s likely content from a ton of legitimate brands! Why? Many brands take deliverability for granted, focusing on content and forgetting to diligently check their inbox placement. Look again – a high percentage of the legitimate emails in your spam folder are probably using their parent domain to send emails instead of a subdomain.

It’s now more important than ever to develop an email strategy that considers how ISPs are going to react to your email campaigns. Sending from only your parent domain increases your risk of landing in spam, but also makes it harder to recover or get off blacklists if you fall victim to an email marketing mistake.

Before we really get into it, let’s go over the basics. What even is an email subdomain?

What is a subdomain?

Let’s back up for a second: a domain is the unique identifier of a specific website. In the below example, ‘hive.co’ is referred to as the parent domain.

The subdomain is the child domain. It’s the prefix to the domain that indicates it’s a subsection of the larger domain. In this example, it’s ‘mail’. You can also think of the subdomain as what comes immediately after the @ symbol.

Last thing: you can put anything you’d like in front of the @ symbol: from michaela@mail.hive.co to spaghetti@mail.hive.co.

What’s the danger of using my parent domain?

Like we mentioned above, by not using subdomains to separate out your sender reputation, your emails are generally more likely to end up in spam. But there are even more risks. If you get to the point where ISPs decide your parent domain isn’t worth inbox placement (e.g. a campaign you send gets marked as spam by a high percentage of recipients or your engagement decreases overtime because you’re not churning your list for inactives), it’s twice as hard to get back on their good side.

Protect your sending reputation

By separating out all of your different types of emails on intentionally dedicated subdomains, from transactional to marketing and support, you protect mistakes on one email subdomain from affecting the sender reputation of the others.

Imagine you accidentally send a draft marketing campaign to your whole list – it doesn’t have the correct subject, and the template is half complete. Often subscribers won’t even check to see where the campaign came from before marking it as spam. If you sent this oops campaign on your marketing email subdomain, the reputation of that email subdomain will get worse, but the reputation of your other email subdomains will be protected!

Hive's Partnership with Clearbanc

Separate out engagement levels

Not only do subdomains protect you from mistakes, they help separate out the types of emails that will naturally get different levels of engagement. As a general rule of thumb, you want to make sure that emails which need to be received and typically get the highest engagement (think: password resets or shipping notices) are getting the best deliverability. Putting your marketing emails on the same subdomain as your transactional emails essentially ensures that the deliverability of your transactional emails will decrease, as marketing emails receive an average of 20-30% opens, while password resets and order confirmations receive an average of 80-90% opens.

Helpful for troubleshooting

Last thing – having separate subdomains for all of the different types of emails you send will also be a lifesaver if you need to troubleshoot a deliverability issue. If you’re sending everything from your parent email domain, and suddenly you see declining engagement, it would be difficult to isolate what’s actually contributing to the decline. With email subdomains, it’s easier to find the root of the problem by identifying which emails have deliverability issues and why. And once you find the issue, correcting it becomes simpler, because you’re only looking at one domain.

What does using an email subdomain look like IRL?

So you’re sold–you’re ready to switch over to email subdomains for your various types of emails! But what does it look like in practice?

Here’s an example from Urban Outfitters. They send their rewards program information from urbanoutfitters@email.urbanoutfitters.com:

Their feedback surveys from urbanoutfitters@f.urbanoutfitters.com:

And their shipping confirmations from urbanoutfitters@t.e.urbanoutfitters.com:

It’s definitely worth noting that I’ve never had an email from Urban Outfitters land in my spam folder!

Wrap Up

Email subdomains are the best way to ensure your emails land in your subscribers’ inboxes. A good step to start seeing a difference in deliverability is separating out your marketing and transactional emails on separate email subdomains. This will help you distinguish your sender reputation for the different types of emails you send while isolating mishaps and helping with troubleshooting. Most importantly, you’ll gain more visibility into the ever changing rules ISPs make for inbox placement, giving you more control over your sender reputation.

Interested in more email deliverability tips? Check out our Ultimate Guide to Email Deliverability for deeper insights!

Hive's Ultimate Guide to Email Deliverability