Set up SMTP relay with Sendmail

Introduction

How to Set up SMTP relay with Sendmail? 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 can use this article to set up your SMTP relay / Smarthost with Sendmail.

Prerequisites

• A VPS or  Dedicated Server where sendmail is installed
• You must be logged in via SSH as sudo or root user. This tutorial assumes that you are logged in as a sudo user.

Step 1: Log in using SSH

You must be logged in via SSH as sudo or root user. Please read this article for instructions if you don’t know how to connect.

Step 2: Configure the MTA

Edit /etc/mail/sendmail.mc  and find the following line

dnl define(`SMART_HOST', `smtp.your.provider')dnl

Replace it with the following line

define(`SMART_HOST', `smtprelay.snel.com')dnl
define(`RELAY_MAILER',`esmtp')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl

Step 3: Regenerate configuration file

Rebuild the configuration file with the following command:

/etc/mail/make

Step 4: Restart the mail server

Restart the mail server by issuing the following command:

service sendmail restart

Step 5: Send test email

echo "Test 1 from $(hostname -f)"|mail -s "Test 1 $(hostname -f)" [email protected]

Conclusion

Congratulations. You have installed SMTP relay / smarthost for your sendmail mail server.