Adding a smarthost - Divert non local messages to another SMTP

PROBLEM

Smarthost Servers

ENVIRONMENT

• atmail mail server

CAUSE

Rerouting required for specific servers

RESOLUTION

Messages to 'non' local accounts will be routed via the remote_smtp router in the Exim configure file /var/lib/atmail/mailserver/roles/ss1ip/templates/exim/routers.j2. The default rule can be modified to relay all outgoing messages via another SMTP-server ( rather then the localhost ) . This is handy for relaying messages to a remote SMTP server for processing, for example a dedicated Antivirus or Anti-Spam appliance/server.

To enable edit the Exim routers configure ansible file and edit as follows: 

Locate:

remote_mail:
driver = dnslookup
domains = !+local_domains
transport = smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
headers_remove = {{ exim_h_spam_report }}
cannot_route_message =
no_more

Change to:

remote_mail:
driver = manualroute
route_list = * smtp.domain.com
domains = !+local_domains
transport = smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
headers_remove = {{ exim_h_spam_report }}
cannot_route_message =
no_more

Where smtp.domain.com is the name of your external smtp server. The IP address of the Atmail server must have relay-access via the external SMTP server to send outgoing messages.

Save changes to the file.

When making changes to the ansible templates, after saving your changes go to your webadmin > Services tab and hit Publish config, for the changes made to become active.

Afterwards, restart Exim. 

systemctl restart exim