So, spam hit again, and I'm moving to a new mail server. As such, it required a lot of work to reconfigure from the old system. I think I've got most things back to working, but if you have trouble with email here, please let me know. The most likely remaining problems are related to people with custom email domains hosted here.
If you're using your own email client, you need to use SMTP authentication with STARTTLS on port 587 (the "submission" port) to send mail now.
Also note, as email is what's being weird, please feel free to post here on the forums if you're having problems.
EDIT: Your ~/.esmtprc file should look something like this now:
identity = user@xepher.net
hostname = mail.xepher.net:587
username = "user"
password = "mypass"
starttls = enabled