This is mainly posted for those people searching on Google.
I just setup a Postfix install with Saslauthd authentication (to an LDAP backend). Postfix refused to do TLS authentication stating (in the maillog):
warning: SASL authentication failure: cannot connect to saslauthd server: No such file or directory
This message isn’t at all helpful in actually TELLING us how to fix this problem. However, it turns out that the build of Postfix Redhat ships looks for Saslauthd’s socket in /var/state/saslauthd while the Redhat shipped Saslauthd version sets itself up in /var/run/saslauthd. Changing the SOCKETDIR (/etc/sysconfig/saslauthd) to /var/state/saslauthd fixes the Postfix issue.
To get testsaslauthd to work I also removed the now deprecated /var/run/saslauthd directory and symlinked it directly to /var/state/saslauthd
Hopefully this will be useful to another frustrated admin like myself.
Stuart