On Wed, Jun 10, 2015 at 03:54:31AM +0000, Viktor Dukhovni wrote:
> Port 587 is not for inter-domain mail delivery. It is for submission
> of mail by users (Outlook, Thunderbird, ...) to the outbound SMTP
> server of their domain. If you're operating an MTA that sends mail
> directly to remote domains, you MUST NOT use port 587.
To be precise, mail you *send* to remote domains MUST go *out* on
port 25. You can of course also operate a submission service for
users that *accepts* mail from your users on port 587.
A submission service template is commented-out in the default
Postfix master.cf file.
--
Viktor.
