Initial tests by Russ have shown that QMTP pushes messages over the net about twice as fast as SMTP.
If you'd like to help the widespread deployment of QMTP, you need to apply the above patch and change your domain's MX records in accordance with the MXPS protocol. For example, if your domain only has one MX host, change its distance to 12801 to let QMTP-enabled hosts know that you're capable of QMTP. If you have two MX hosts, make the first MX be distance 12801 and the second be distance 12817 (+16). Add 16 to the distance for each additional MX. Note that your MX hosts still need to support SMTP for clients that don't support QMTP.
In addition, you need to set up a tcpserver instance for qmail-qmtpd. You can use the tcpserver command line you use for qmail-smtpd as an example; simply change the port (usually either '25' or 'smtp') to '209' or 'qmtp' (if it's in /etc/services) and replace /var/qmail/bin/qmail-smtpd with /var/qmail/bin/qmail-qmtpd. Copy this new line into the same file you use to start tcpserver for qmail-smtpd. If you're running qmail-smtpd under supervise, create a new service for qmai-qmtpd using your qmail-smtpd service layout as an example, making the changes to the command line noted above in your run file.
Save bandwidth! Help deploy QMTP!