I’m not sure why I ever run an `apt-get upgrade` on Debian as I usually spend the next week fixing the issues it’s created. Today’s problem was preventing postfix authenticating smtp users with saslauthd and thus stopping e-mail sending. The log file (/var/log/mail.err) produced the oh so helpful message “SASL LOGIN authentication failed: no mechanism available”.
Google wasn’t much use in diagnosing this as a few people had reported having the issue on Debian but no solution was available. I fixed it by downgrading 5 sasl packages to their Squeeze releases. Commands below:
dpkg -i *.deb