I did a complete clean install of 11.10 earlier today.
Lo and behold, mail sending not working.
I did the workaround and that didn't work, so tried editing smtpd.conf to this...
mech_list: plain login pam
sql_passwd: <Not gonna tell ya>
sql_select: select password from mail_user where login = '%u'
Restarted postfix and saslauthd and nope. still can't send.
The client is set to use a normal password and STARTTLS. Is that correct?