Update to postfix-2.0.16 or greater causes SMTP Auth to break. The original postfix rpm owned the /etc/sysconfig/saslauthd file; the newer version no longer does. If postfix was installed prior to updating, then this file is removed, which causes sendmail-8.12.10 SMTP AUTH to break.
|| Ensim Pro, Ensim Basic
|| Red Hat Enterprise
The fix is to recreate /etc/sysconfig/saslauthd, with the contents "MECH=pam"