How to Set Up SMTP Relay Between 2 Postfix SMTP Servers on Ubuntu

Previously we discussed setting up Postfix SMTP relay with mailjet, which is useful when you have to use a commercial SMTP relay service. This tutorial will be showing you how to set up SMTP relay between 2 Postfix SMTP servers on Ubuntu.

Use Case Scenario

Let’s say there are two servers: server A and server B. You have set up a full-featured mail server on server A with Postfix as the SMTP server. You can use it to send emails directly to recipients, because port 25 isn’t blocked.

Later you use server B to set up a website, which needs to send notification emails to users. You can set up another mail server on server B, but it’s a waste of time and hardware resources. A more sensible solution is to install Postfix SMTP server on server B and configure it to send emails via server A, which can relay emails from server B to the final recipients. Server A has built up its IP reputation, so you don’t have to build IP reputation for server B.

Read full tutorial here: https://www.linuxbabe.com/mail-server/smtp-relay-between-2-postfix-smtp-servers