I've deployed a Turnkey LAMP server. The website has email capabilities but in /var/mail/www-data I find little love letters like this:
host mx1.mailhop.org[18.104.22.168] said: 504 5.5.2
<localhost>: Helo command rejected: need fully-qualified hostname (in reply
to RCPT TO command)
I have dug into PostFix (etc/postfix/main.cf), php.ini, and hosts. I've changed and qualified every setting that I can get my hands on, but nothing changes the hostname that is presented to the remote SMTP server when the SMTP header is sent out. I've even directed messages to a mail server that I manage so that I can see the log entries as the email is recieved and it stubbornly insists on identifying itself as "localhost" whenever it attempts to deliver a mail message.
What am I missing? I am not a Ubuntu or any flavor of linux master so I need some very specific explanation about how all these different processes fit together so I can understand this system. I'm pretty good at digging around and figuring out what I need to know, but I'm just spinning in circles at the moment.
All help is appreciated.