Lately my TP server was having problems sending emails to Yahoo addresses. Most emails were put under mail queue for hours. I decided to setup a Smart Host under Exim. If the recipients' emails are Yahoo addresses, the Smart Host will be engaged.

There are two SMTPs that can be used - Gmail or DynDNS. While Gmail's smtp is free, a copy of the email will be placed under the SENT EMAIL folder once it is processed. This will take up the 2Gb space soon if you have a lot of emails to process. Also, there is no one-click solution to purge emails under SENT EMAIL folder.

So I decided to use DynDNS.com's MailHop Outbound service. It is sold at the block of 150 relays per day @ $15/year. Meaning, you can process 150 mails each day. If you have more, then you have to purchase more blocks. To find out how many emails you have processed under DynDNS, log into your account and view the statistics.

# Select the SMTP to use:
For Gmail:
First, enable POP for your gmail account. You do that in the “Forwarding and POP” section of the settings.

For DynDNS:
Subscribe to the MailHop Outbound service.

# Next, create a domain list. This domain list will hold the list of domains to send via gmail or DynDNS, one domain per line. Save your domain list as /etc/exim/gmail.domains or /etc/exim/dyndns.domains .

# Then, add a domain list to your exim configuration. For WHM/cPanel, go to Exim Configuration Editor >> Advanced Editor and enter this line below the very top box of Exim Configuration Editor:




# Seach for the string "begin authenticators". In the box after this string, create an authenticator.




Note that in a default exim configuration there are usually no authenticators, so don’t forget the begin authenticators statement if this is your first one.

# Under the ROUTER CONFIGURATION box, add a router:




# Under the TRANSPORTATION CONFIGURATION box, forcing it to use AUTH and TLS (TLS is not required for DynDNS):




# Save Exim config and restart Exim.