Dan, thanks for catching that! Ok, so now I've gotten further!
pwcheck_method:saslauthd
mech_list: login plain
saslauthd_path: /var/run/saslauthd/mux
allowplaintext: 1
and the perms look like this:
[#4136] ls -l /var/run/saslauthd/mux
srwxrwxrwx 1 root root 0 Jun 17 13:11 /var/run/saslauthd/mux
[#4137] ls -ld /var/run/saslauthd
drwx--x--- 2 root sasl 140 Jun 17 13:11 /var/run/saslauthd/
[#4138] grep sasl /etc/group
sasl:x:45:smmta,smmsp
At this point, what made it work was chmodding the /var/run/saslauthd to 777. So sendmail must be running in some other group.
I have to say that this was bloody difficult to debug. It would have been so kind to output a simple 'open failed: /var/run/saslauthd' or something similar rather than a generic error!
Thanks for your help. Now on to the next problem, why isn't sendmail allowing me to send (relay) mail now that the connection is properly authenticated...
Michael Grant