Mailgun - Subdomain vs Generic Domain


I’ve set up a subdomain in Mailgun and its working fine.

  1. Should I use one subdomain for all of my client’s sites/domains?

For example,

or should I set up a new subdomain for each clients site/domain?

I’m not sure what is best practice in terms of authority and appearance.

Some people say to set up a new smtp user under the generic domain for each client, like

or is it better to add individual subdomains for each client?

Thank you.

I was wondering the same thing.

If you want your clients’ emails to come from something that seems more official, I’d set up,, and so forth. This gives each client their own sending subdomain and does the following:

  • separates any sort of transactional mail that may be mismarked as spam or phishing from legit client-generated email that they would expect to be delivered for sales and such
  • gives the transactional mail the authority of having an SPF record and being signed by a subdomain of the actual client root domain. Things like password reset emails or Wordfence notifications can then be trusted by your clients’ users; anyone can send an SPF/DKIM complete email from and that’s often explicitly what phishing schemes do. In terms of authority, you’re best off sending from a subdomain of a client domain that their users trust as being a source of truth
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Thanks again, Lucas.

being signed by a subdomain of the actual client root domain.

I was thinking that must be essential, the generic method just doesn’t fit.