Postfix and Dovecot SASL
Since version 2.3, Postfix supports SMTP AUTH through Dovecot SASL.
If using Postfix obtained from a binary (such as a .rpm or .deb file), you can check if Postfix was compiled with support for Dovecot SASL by running the command: postconf -a.
Once you have verified that your installation of Postfix supports Dovecot SASL, it's very simple to configure:
Configuration
service auth {
...
unix_listener /var/spool/postfix/private/auth {
mode = 0660
# Assuming the default Postfix user and group
user = postfix
group = postfix
}
...
}
# Outlook and Windows Mail works only with LOGIN mechanism, not the
# standard PLAIN
auth_mechanisms = plain loginsmtpd_sasl_type = dovecot
# Can be an absolute path, or relative to $queue_directory
# Debian/Ubuntu users: Postfix is setup by default to run chrooted, so it
# is best to leave it as-is below
smtpd_sasl_path = private/auth
# On Debian Wheezy path must be relative and queue_directory defined
#queue_directory = /var/spool/postfix
# and the common settings to enable SASL:
smtpd_sasl_auth_enable = yes
# With Postfix version before 2.10, use smtpd_recipient_restrictions
smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destinationUsing SASL with Postfix Submission Port
When Dovecot is used as the authentication backend for Postfix, it is good practice to use a dedicated submission port for the MUAs (TCP 587).
Not only can you specify individual parameters in master.cf overriding the global ones, but you will not run into internet mail rejection when the Dovecot Auth Mechanism is unavailable.
In this example, Postfix is configured to accept TLS encrypted sessions only, along with several other sanity checks:
Verification of alias ownership via Login Maps
Domainname and recipient plausibility
submission inet n - n - - smtpd
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_sasl_type=dovecot
-o smtpd_sasl_path=private/auth
-o smtpd_sasl_security_options=noanonymous
-o smtpd_sasl_local_domain=$myhostname
-o smtpd_client_restrictions=permit_sasl_authenticated,reject
-o smtpd_sender_login_maps=hash:/etc/postfix/virtual
-o smtpd_sender_restrictions=reject_sender_login_mismatch
-o smtpd_recipient_restrictions=reject_non_fqdn_recipient,reject_unknown_recipient_domain,permit_sasl_authenticated,rejectDovecot Authentication via TCP
If Postfix and Dovecot are running on separate servers, you can also authenticate via TCP. For Dovecot, set up an inet_listener:
service auth {
inet_listener {
port = 12345
}
}smtpd_sasl_path = inet:dovecot.example.com:12345
smtpd_sasl_type = dovecot