qmHandle is a perl script for managing Qmail mail queues.

On SME version 8, which uses CentOS 5 as the base, you can install qmHandle like this:

rpm -Uvh http://www6.atomicorp.com/channels/atomic/centos/5/i386/RPMS/qmhandle-1.3.2-4.el5.art.i386.rpm

If you already have the Atomic repository configured, you can just:

yum install qmhandle --enablerepo=atomic

You can see a command reference like this:

qmhandle.pl

or list mail queues like this:

qmhandle.pl -l

You can tell Qmail to retry sending all messages now like this:

qmhandle.pl -a

You can delete all queued messages and restart Qmail like this:

qmhandle.pl -D

service qmail restart