I have just setup my debian mailserver using postfix, dovecot and SASL as explained in this excellent tutorial. I have used postfixadmin to setup a virtual list of aliases for sending firstname.lastname@example.org to their email (for example, email@example.com). This works for receiving but for sending out with their new email I need to authenticate them. Question is, where does this authentication come from? Because they're aliases they do not have an account on the server! Can anyone help?
You need to do three things, create a file (or DB) with
domain username:password style entries, postmap (or create a query that will find the info) that file, then tell postfix to use those entries when sending to servers who need them:
smtp_sasl_auth_enable = yes # you should have this already
smtp_sasl_password_maps = hash:/etc/postfix/smtp_sasl_passwd # this is the postmap variety smtp_sasl_password_maps = mysql:/etc/postfix/mysql_sasl_passwd # MySQL version
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