I have set up SMTP relay using postfix on number of VPS instances we manage. Relay is used for sending errors and reports (duplicity, httpok, zope, crons ...) from services on those VPSs. They are sent to our dreamhost maintenance mail.

SMTP host to relay to is on dreamhost, which we manage. I've created a individual mailbox (e.g. [email protected]) for every project/VPS instance where we also have control over SMTP server.

But the problem is not all of those VPS instances have dreamhost set in MX record. Some of them use google and others use our local ISP's SMTP server, to which I do not have access.

Is there any issue if I use dreamhost as relay host on VPS instances that do not have dreamhost SMTP server under their MX record?

I've done a lot of reading on the subject, but as you've probably noticed, I'm not a sys admin, so if there are any misconceptions above, please do tell.

1 Answer 1


Ok, so:

  • MX records: tell the outside world how to deliver e-mail to you.
  • SMTP relay/smarthost: act as relay for e-mail you send.

The question is "will dreamhost relay e-mail from unknown domains"?

... Maybe

In general, SMTP relays do not forward from unknown senders (SPAM/security/etc.), but dreamhost may have a policy that "trusts" the dreamhost VPS instances.

Because the dreamhost relay's policy controls this behavior, you can test and verify, or open a query/ticket with dreamhost to find out their policy.

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