Qmail-ldap with SMTP Auth

Authenticated SMTP with SMTP-AUTH

SMTP AUTH is particulary useful when you have roaming users as well as users with dynamic IP assigned by their ISPs. These users can now use your SMTP server to relay their mails even if their IP or network is not listed in your allowed list of networks/IPs in qmail-smtpd.cdb file. Authenticated SMTP will allow such users to enter their credentials which are verified against their account entry in qmail-ldap and upon successful authentication they will be granted access to relay mails using your server regardless of their current IP or network. Read more about relaying in my mail relaying document.

In order to qmail-smtpd support this functionality you have to edit current /var/qmail/boot/qmail-smtpd/run script to invoke auth-smtp program installed with qmail-ldap in your installation. Open this file in your favorite editor and look for the following lines towards end of file.
exec \
envuidgid $QUSER \
tcpserver -v -URl $ME -x$QMAIL/control/qmail-smtpd.cdb \
${CONCURRENCY:+"-c$CONCURRENCY"} ${BACKLOG:+"-b$BACKLOG"} 0 smtp \
$PBSTOOL \
$QMAIL/bin/qmail-smtpd

Add command $QMAIL/bin/auth_smtp /usr/bin/true to the last line, so now the last line in your run script become..
exec \
envuidgid $QUSER \
tcpserver -v -URl $ME -x$QMAIL/control/qmail-smtpd.cdb \
${CONCURRENCY:+"-c$CONCURRENCY"} ${BACKLOG:+"-b$BACKLOG"} 0 smtp \
$PBSTOOL \
$QMAIL/bin/qmail-smtpd $QMAIL/bin/auth_smtp /usr/bin/true

Now add these variables to your qmail-smtpd.rules file
:allow,SMTPAUTH="AUTHREQUIRED",NOPBS=""

So now your qmail-smtpd.rules file will look as shown below
127.:allow,RELAYCLIENT=""
:allow,SMTPAUTH="AUTHREQUIRED",NOPBS=""

Now you have to rebuild the cdb file from qmail-smtpd.rules file. For this you have to issue following command as root. The variable SMTPAUTH tells qmail-smtpd that authorization is required before relaying mail from your server. Next variable NOPBS tells smtpd not to use PBS (POP Before SMTP). You do not need this since you are using SMTP AUTH. This may be required when you are using clustered servers but not now.
# tcprules qmail-smtpd.cdb rules.tmp < qmail-smtpd.rules

You have to restart the smtpd service for these changes to take effect. To do this issue following command as root.
# svc -t /service/smtpd

To test this setup try sending mail from some other host using sender's address on mail envelop as your servers default domain. It should ask you for authentication. If this works, you are done with SMTP AUTH. Don't forget to verify the service is running using svstat command as follows before you test.
# svstat /service/smtpd
/service/smtpd: up (pid 26698) 14 seconds