send FQDN in SMTP HELO
I have in my smtp server (postfix) config:
smtpd_helo_restrictions = ...,
My home PC (windows 7) is behind a WiFi router so it does not see the FQDN assigned by my ISP. It's computer name is just XPS.
So when trying to send a test message I was getting a "helo rejected. need a fully-qualified hostname" error. I know what it means and how to fix it, but other users may not.
So it may be worth checking the hostname on startup and issuing a warning if it's not fully-qualifies and/or valid (like e.g. "Joe's computer" is invalid). And/or provide a setting for the hostname to use with SMTP HELO? Or at least add something to documentation.
FWIW this didn't happen in thunderbird so they must be sending something that looks like a fully-qualified hostname even when one is not available from the system.