Postfix to use a third party SMTP server

3 Mar

This instructs postfix to use a third party SMTP server. It’s useful when you want to relay e-mail from an internal server which uses a dynamic IP address.

Ensure postfix is installed, and let’s have all e-mail sent to root relay to an external e-mail address:

[bash]nano /etc/postfix/sender_canonical[/bash]
[text]root     youremail@provider.tld[/text]

Postfix requires the modifications to be hashed:

[bash]postmap hash:/etc/postfix/sender_canonical
postconf -e "sender_canonical_maps=hash:/etc/postfix/sender_canonical"[/bash]

Now let’s instruct postfix to use third party SMTP to route e-mail:

[bash]
nano /etc/postfix/main.cf
relayhost = yoursmtp.provider.tld
service postfix restart[/bash]

Finally update system aliases:

[bash]
nano /etc/aliases
root:   email@domain.tld
newaliases[/bash]