What happens if you choose the wrong subdomain? Does everything explode and the submarine sinks to the bottom of the ocean? Not really, but there are indeed some considerations around choice of subdomain for your various types of email messages.
I recently tackled this topic in my Valimail "Ask Al" video series. If you're the type of person who prefers to watch and listen rather than read, I’ve embedded the video here for you. Or, if you’re all about that written content, stick with me and we’ll dive into it together below.
And this is a question I get surprisingly often. IT administrators frequently need to configure a specific subdomain to point toward an Email Service Provider (ESP). Sometimes the platform requires it for technical reasons; other times, it’s just a best practice for organization and auditing.
But before we talk about what to pick, we have to talk about what not to pick.
Avoid Lookalike Domains
I cannot stress this enough: Stay away from cousin domains or lookalikes. If your main domain is example.com, consider:
Real subdomains: e.example.com, m.example.com, news.example.com, potato.example.com.
Why does this matter? When you use a lookalike domain, you are training your customers to trust something that is "almost" your brand. You are effectively lowering the bar for phishers and bad actors who love to spin up convincing "close-but-not-quite" domains. Stick to your actual organizational domain. Your real domain.
There are a lot of lookalike domains configured in various email service providers today. That’s usually because a lot of those configurations were initially set up years ago, and nobody has gone back to update it since. Remember that just because you see it out in the wild, does NOT mean it’s still a best practice.
Why Use a Subdomain at All?
If you're wondering why you can't just send everything from your top-level domain (example.com), there are three big reasons:
Clarity and Auditing: Using e.example.com for marketing makes your logs and tracking much cleaner. You’ll always know exactly where that traffic originated.
Technical Necessity: Many ESPs require a dozen or more DNS entries. If you try to put these at the top level, they often conflict with existing records (like your website or corporate email). A subdomain gives you a "clean room" to work in.
Reputation Segmentation: A subdomain provides a buffer. While spam filters are smart enough to link a subdomain to the main organizational domain, having a dedicated subdomain for bulk mail can help insulate your critical corporate/executive communications if your marketing reputation takes a temporary hit.
But, ultimately, YMMV. If it’s possible to send as the top level of your domain, and authenticate everything correctly, that’s not inherently evil. Especially if you’re a small sender and not juggling a bunch of different email send platforms. So, keep all of this in mind and decide on what makes the most sense for you.
Naming That Subdomain
When it comes to the actual name, keep it flexible and neutral.
Don't Box Yourself In: Avoid names like marketing.example.com or sales.example.com. What happens when you start sending transactional receipts, product updates, or customer education from that same platform? Suddenly, a "marketing" label feels inaccurate.
Avoid "Spammy" Keywords: This should go without saying, but don't use blast.example.com or spam.example.com. You don't want a recipient to look at the "From" address and immediately think "unwanted junk."
Keep it Short: Mobile email client real estate can be limited. Shorter subdomains might actually look cleaner in the "From" field. My guidance? Go for choices like m.example.com, e.example.com, or msg.example.com.
Related Bits and Bobs
Once you’ve picked your subdomain name, you’re not quite done. There are a few other things you should keep in mind.
Warm It Up: You cannot go from zero to 100,000 emails overnight on a new subdomain. You need a controlled ramp-up plan. (I highly recommend checking out Jennifer Nespola Lantz’s guide to IP warming for the specifics).
Watch Your DMARC Records: Some ESPs will automatically create a DMARC record for your new subdomain. I've seen cases where they set it to p=reject without an aggregate reporting (RUA) address. If this happens, it can mess things up. If you see a conflicting record, ask your ESP to remove it.
Google Postmaster Tools: Don't forget to register the new subdomain here. It’s the best way to get direct feedback from Gmail regarding your reputation and complaint rates.
There you have it. Not too complicated, I hope. Just remember to use your real domain, pick something short and simple, and remember to configure everything and warm it up properly.
And don't forget to follow my Ask Al video series (aka "Your Email Authentication and Deliverability Questions Answered). Find it here on Youtube.
What happens if you choose the wrong subdomain? Does everything explode and the submarine sinks to the bottom of the ocean? Not really, but there are indeed some considerations around choice of subdomain for your various types of email messages.
I recently tackled this topic in my Valimail "Ask Al" video series. If you're the type of person who prefers to watch and listen rather than read, I’ve embedded the video here for you. Or, if you’re all about that written content, stick with me and we’ll dive into it together below.
And this is a question I get surprisingly often. IT administrators frequently need to configure a specific subdomain to point toward an Email Service Provider (ESP). Sometimes the platform requires it for technical reasons; other times, it’s just a best practice for organization and auditing.
But before we talk about what to pick, we have to talk about what not to pick.
Avoid Lookalike Domains
I cannot stress this enough: Stay away from cousin domains or lookalikes. If your main domain is example.com, consider:- Real subdomains: e.example.com, m.example.com, news.example.com, potato.example.com.
- Lookalike/Cousin domains (avoid): example-email.com, examplemail.com, marketing-example.com, example.net.
Why does this matter? When you use a lookalike domain, you are training your customers to trust something that is "almost" your brand. You are effectively lowering the bar for phishers and bad actors who love to spin up convincing "close-but-not-quite" domains. Stick to your actual organizational domain. Your real domain.There are a lot of lookalike domains configured in various email service providers today. That’s usually because a lot of those configurations were initially set up years ago, and nobody has gone back to update it since. Remember that just because you see it out in the wild, does NOT mean it’s still a best practice.
Why Use a Subdomain at All?
If you're wondering why you can't just send everything from your top-level domain (example.com), there are three big reasons:- Clarity and Auditing: Using e.example.com for marketing makes your logs and tracking much cleaner. You’ll always know exactly where that traffic originated.
- Technical Necessity: Many ESPs require a dozen or more DNS entries. If you try to put these at the top level, they often conflict with existing records (like your website or corporate email). A subdomain gives you a "clean room" to work in.
- Reputation Segmentation: A subdomain provides a buffer. While spam filters are smart enough to link a subdomain to the main organizational domain, having a dedicated subdomain for bulk mail can help insulate your critical corporate/executive communications if your marketing reputation takes a temporary hit.
But, ultimately, YMMV. If it’s possible to send as the top level of your domain, and authenticate everything correctly, that’s not inherently evil. Especially if you’re a small sender and not juggling a bunch of different email send platforms. So, keep all of this in mind and decide on what makes the most sense for you.Naming That Subdomain
When it comes to the actual name, keep it flexible and neutral.Related Bits and Bobs
Once you’ve picked your subdomain name, you’re not quite done. There are a few other things you should keep in mind.Comments
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