Routing all mails for a specific domain to a smarthost

https://help.comodo.com/topic-157-1-288-4544-.html

Configuring Exim to use a Smarthost


Routing all mails to a smarthost :

To configure the mailserver Exim, edit your Exim configuration file (e.g. /etc/exim/exim.conf).

Add in the routers section (after begin routers):

 spamgateway_smarthost_router:
  driver = manualroute
  transport = spamgateway_smarthost_transport
  route_list = $domain mxpool1.spamgateway.comodo.com::587
  no_more

Make sure the local mail route is before smarthost, if you don’t want local mail to be forwarded. Add in the transports section (after begin transports):

spamgateway_smarthost_transport:
  driver = smtp
  hosts_require_tls = *

Routing all mails for a specific domain to a smarthost:

Note: The information below relates to a very specific customer requirement and is not recommended for most deployments. A configuration like this can cause problems which will be hard to troubleshoot. Unless you are sure you need to use this setup, please explore the other available options for routing mail.

Put the domain in place of the $domain value in the route_list (above). For multiple domains you can use:

  route_list = domain.example.com mxpool1.spamgateway.comodo.com::587 ;
               domain.example.org mxpool1.spamgateway.comodo.com::587

Restart Exim for the changes to take effect.