Set up SMTP relay on Plesk with Postfix

Introduction

If you want or need to set up your mail server to send all outgoing mail to a specific server that will handle the delivery to the recipients you need to set up an SMTP relay or smarthost.

Prerequisites

• You need to know the hostname of the SMTP server which is going to relay the mail for your mail server, which is smtprelay.snel.com in our case
• This article assumes that no authentication is necessary on the SMTP relay server
• This article is written for Plesk with Postfix
• You need to have the SSH login details of your server ready

Step 1: Log in with SSH

Log in as root. Please see this article for instructions if you don’t know how to connect.

Step 2: Configure the MTA

Update the postfix configuration by issuing the following commands:

postconf -e 'relayhost = [smtprelay.snel.com]:587'
postconf -e 'smtp_tls_security_level = may'

Step 3: Restart the mail server

Restart the mail server by issuing the following command:

service postfix restart

Conclusion

Congratulations, you have now installed SMTP relay / smarthost for your mail server.