Brain Goo

D. J. Bernstein’s Qmail, now in the public domain, is a powerful yet clumsy SMTP messaging system. One of the most common problems is updating the rules for allowing SMTP relay, or denying the same.
If you qmail-smtpd under tcpserver, the following will update relay allow and relay forbid rules.
Create a file called /etc/tcp.smtp and [...]

[Read more →]

/var/qmail/bin/qmail-showctl will show you the running config.
Qmail does not allow you to restrict max recipients or max messages per session. I saw reference to a plugin to handle these controls, but do not know the name of it.
You can restrict max message size in /va/qmail/control/databytes
Example:
$ cat /var/qmail/control/databytes
10485760
That’s a 10MB limit
Adverts:
The qmail Handbook
qmail
Running qmail

[Read more →]

Qmail smtproutes can only handle one route per egress domain name.
Example:
example1.com:10.0.0.1
example1.com:10.0.0.2
Will send mail only to 10.0.0.1 The second entry will be ignored.
You are better off using round-robin DNS or submitting a patch to handle priority routing.
Adverts:
The qmail Handbook
qmail
Running qmail

[Read more →]