Recently I upgraded from 10.04 LTS to 12.04 LTS, and everything worked fine, Apache2, MySQL, PHP - except from postfix mailer server. I got this error:
535 5.7.8 Error: authentication failed: authentication failure
After looking on the web I found this article: http://krisweston.com/2012/postfix-dovecot-and-mysql-on-ubuntu-12-04-lts/
I narrowed my error down to the
/etc/postfix/sasl/smtpd.conf and found out that the format of this file had changed. This is the new format:
pwcheck_method: saslauthd mech_list: plain login log_level: 7 allow_plaintext: true auxprop_plugin: sql sql_engine: mysql sql_hostnames: 127.0.0.1 sql_user: mailadmin sql_passwd: yourpass sql_database: mail sql_select: select password from users where email = '%u@%r'
Use this format, and I hope it will work for you!