28.10 Sending Mail via an SMTP Relay Server
An alternative to configuring a mail server to handle outgoing email messages is to use an SMTP Relay service. As previously discussed, a number of services are available, most of which can be found by performing a web search for “SMTP Relay Service”. Most of these services will require you to verify your domain in some way and will provide MX records with which to update your DNS settings. You will also be provided with a username and password which need to be added to the postfix configuration. The remainder of this section makes the assumption that postfix is already installed on your system and that all of the initial steps required by your chosen SMTP Relay provider have been completed.
Begin by editing the /etc/postfix/main.cf file and configuring the myhostname parameter with your domain name:
myhostname = mydomain.com
Next, create a new file in /etc/postfix named sasl_passwd and add a line containing the mail...