feat(postfix): Allow relay setup

This patch updates the container image to allow relayhosts with TLS
enabled.

images/postfix/Containerfile

@@ -6,7 +6,7 @@ RUN apk add --no-cache ca-certificates rsyslog supervisor
 RUN update-ca-certificates
 
 
-RUN apk add --no-cache postfix
+RUN apk add --no-cache postfix cyrus-sasl cyrus-sasl-login
 
 RUN mkdir /var/spool/postfix/etc && echo "smtp		25/tcp		mail		# Simple Mail Transfer" > /var/spool/postfix/etc/services
 

images/postfix/config/main.cf

@@ -64,7 +64,7 @@ smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
 #smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
 #smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
 
-#smtp_tls_policy_maps = lmdb:/srv/tmp/tls-policies
+smtp_tls_policy_maps = lmdb:/srv/tmp/tls-policies
 
 ########
 ##
@@ -156,6 +156,18 @@ virtual_mailbox_maps = lmdb:/srv/tmp/mailboxes
 virtual_mailbox_domains = lmdb:/srv/tmp/domains
 local_recipient_maps = $virtual_mailbox_maps
 
+## Relay config
+
+sender_dependent_relayhost_maps = lmdb:/srv/tmp/relayhosts
+
+## SMTP sasl
+
+smtp_sasl_auth_enable = yes
+smtp_sasl_security_options = noanonymous
+smtp_sasl_tls_security_options = noanonymous
+smtp_sasl_password_maps = lmdb:/srv/tmp/sasl_passwd
+smtp_tls_note_starttls_offer = yes
+
 ########
 ##
 ## Miscellaneous