I'm new; I had mail issue that I've only been able to research 1/2 the solution... help very much appreciated!
Cobalt Linux release 6.0
I can send mail to internal users, I can send mail to domains outside my server, sendmail works from my contact webpage, but I cannot receive email from outside the server.
History of issue:
warning message rec'd while using email that
Mailbox vulnerable - directory /var/spool/mail must have 1777 protection
I looked up the permissions, seemed reasonable, so I changed. Then no email allowed.
Changed back using
chmod 775 /var/spool/mail
...but only user-to-user email worked and no sendmail from webserver
so research and found I should
chmod 775 /var/spool/mail (and)
chown root.mail /var/spool/mail
...user-to-user works, sendmail works
...but email from external server is rejected:
Unable to deliver message to: <firstname.lastname@example.org>
Delivery failed for the following reason:
501 5.1.8 <email@example.com>... Domain of sender address
does not exist, while talking to ip_of_my_server
This has been a permanent failure. No further delivery attempts will be made.
It looks as if my server cannot resolve domains, but /etc/resolv.conf looks like:
Thanks in advance for the help.