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When web apps on my VPS use the PHP built-in mail function, some domains (like att.net) bounce emails back. /var/log/mail.log reveals:

550 [PERMFAIL] att.net requires valid sender domain (in reply to RCPT TO command)

Basically the MAIL FROM line is something like <user@myhost> when it should be <user@myhost.com>, so AT&T's mail server doesn't like it.

I'm not entirely sure if my /etc/hostname file needs to be myhost or myhost.com. Any time I try to change it to myhost.com, upon reboot it reverts back to myhost.

I'm at a loss here.


Apparently /etc/hostname (according to Google searches) should be just the hostname, not the FQDN. If I type hostname --fqdn, then I get the FQDN.

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1 Answer 1

Well, that was a fast self-solution!

The myorigin line in /etc/postfix/main.cf was set to /etc/hostname. I commented out that line so it defaults to $myhostname which is set to my FQDN. All is well.

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