# allows us to do stuff like dovecot-side sieve filtering.
mailbox_transport = lmtp:inet:127.0.0.1:2424
-# use dovecot SASL for SMTP access
+# to authenticate on SMTP, we need a SASL mechanism; we talk to dovecot
+# for this, since it provides one
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes