Do domain names affect deliverability?

Leo Hatton

Got a business idea? Thought of a name yet? Okay, let’s check the domain name, hopefully it's avail.. taken. Not to worry, let’s do a subtle varia.. taken. Perhaps the alternative spell.. aaaand it’s taken.

Small wonder we have startups calling themselves Yoose, Qeeple, Ubooly and suchlike.

Well, to add to the numerous considerations when choosing a domain name for your business, or simply a sub-domain for your outbound email marketing activities; here’s another one (sorry).

Did you know the name you choose can affect the deliverability of your emails?

Well, it can, and sometimes the effects can be catastrophic.

We worked with a company who were having real trouble getting even basic one-to-one emails to their clients. The analysis revealed an unusual problem, which took even us by surprise. Their standard company email signature contained, as most do, a link to their site. This was the link:


Innocent enough, but a spam-filtering system scanning through the mail would see this pattern:


.exe in an email? The horror.

As the file-extension for Windows executables, this is almost universally blocked by spam-filtering systems as one of the most common attack vectors for viruses/malware etc. Yes, it’s not attached as a file, but if a primitive mailscanner reads .exe, it’s not going to take the chance on a potentially nefarious embedded executable.

Luckily, this is easily fixed by changing the link slightly:


Voila, no .exe pattern, problem solved.

Bad luck and subdomains

In a constantly fluctuating environment, the words and phrases ignored by spam-filtering systems one minute can be frowned-upon the next. Simple bad luck can have your chosen domain/sub-domain flagged as a spam-heavy word, but some prior thought can minimise the risks.

We wouldn’t, for example, choose as a sending subdomain. However, on the other end of the Captain Obvious scale, we’d also stay clear of something like or if we're talking full sending addresses.

Even purely on string-searching, this kind of behaviour makes it easy for spam-filtering technologies to sort your mail into the 'appropriate' folder (read: spam folder).

As long as it comes from the right domain, very few people notice or care about the full sending address, so you really do have a lot of options for choosing something innocuous to spam-filters.

Choose wisely and, I don't know, perhaps test your choices before you send with some kind of pre-emptive email deliverability system.

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