I've followed the instructions from the "Virtual Users and Domains with Postfix, Courier, and Mysql" and am having an issue with logging in. The setup receives emails fine, and apparently sends them fine too, because it will forward to an external email if asked too. The trouble is that I can not log in to the account. Log in attempts return "Login Failed". The log at /var/log/mail.log shows Code: Jan 25 15:07:55 web1 courierpop3login: Connection, ip=[::ffff:18.104.22.168] Jan 25 15:08:18 web1 authdaemond.mysql: failed to connect to mysql server (server=localhost, userid=mail_admin.) Jan 25 15:08:23 web1 courierpop3login: LOGIN FAILED, ip=[::ffff:22.214.171.124] I see 250-STARTTTLS and 250-AUTH in ehlo. I've checked all the config files to make sure the username and password are correct for mysql connections, and it seems they are. I am pretty sure that I'm not using the wrong email address and password to cause the login failure, because the log says it can't connect to the DB. I would appreciate it if someone could tell me where to start looking for a configuration problem that would cause it to not connect to the DB. Thanks in advance for your help.