Configure exim4 to send messages by smarthost, no local mail

This option of exim4 configuration is suitable for a client system which is not responsible for a local e-mail domain. All locally generated e-mail is sent to the smarthost.

• Smarthost FQDN: mail.dev.local
• Client: deby01.dev.local

Here are few simple steps to configure:

1. The easiest way is to reconfigure exim4-config package:

   dpkg-reconfigure exim4-config
   

2. General type of mail configuration:
      mail sent by smarthost; no local mail
   System mail name:
      deby01.dev.local
   IP-addresses to listen on for incoming SMTP connections:
      127.0.0.1
   Other destinations for which mail is accepted:
      deby01.dev.local
   Visible domain name for local users:
      deby01.dev.local
   IP address or host name of the outgoing smarthost:
      mail.dev.local
   Keep number of DNS-queries minimal (Dial-on-Demand)?
      No
   Split configuration into small files?
      No
   

Let verify it is working:

echo "test message" | mail -s "test" user1@dev.local

... exim4 log (file /var/log/exim4/mainlog):

1PmoNq-0001or-55 <= root@deby01.dev.local H=deby01.dev.local (localhost) [192.168.XX.XXX] P=esmtps X=TLS1.0:RSA_AES_256_CBC_SHA1:32 S=715 id=E1PmoNq-0001f6-08@localhost
1PmoNq-0001or-55 => user1  R=local_user T=maildir_home
1PmoNq-0001or-55 Completed

At this point user1 should be able to receive your test message.