How to change the default SMTP port for Postfix

If you need to change port 25 on your Postfix mail server to maintain security, you can see our guide for it.

by Hanife Diktas

August 6, 2023

in How To

How to change the default SMTP port for Postfix

When your service provider has blocked port 25, you may need to change it to 587 from your mail server. Port 25 generates security vulnerabilities during mail sending if it does not perform any authentication process. That is why service providers allow sending mail by authenticating over port 587. If you are using Postfix as the mail server, you can fix the problem by following the steps below.

Changing the default SMTP port for Postfix

Step 1: Open master.cf via nano

Open the Postfix configuration file which is located under /etc/postfix/master.cf.

Step 2: Activate SMTP

Activate SMTP by removing the ” # ” sign in front of smtpd from the configuration file and exit the file by saving it.

Step 3: Restart Postfix

systemctl restart postfix

Once you restart the postfix, you successfully change the port on Postfix with 587; your mail server is now secure.

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Hanife Diktas

Hanife Diktas is the Sales & Marketing Manager of IT Business Review. Hanife started her career in the manufacturing sector in the marketing and sales department. Hanife worked in industrial equipment, renewable energy, and technology sectors. Hanife Diktas did her bachelor's degree in business administration and completed a master's degree in management at Yeditepe University in Istanbul, Turkey. Hanife is a Linux user, and she also contributed to AlmaLinux OS at the beginning of the project. Hanife focuses on web hosting, cloud computing, data centers, cybersecurity, Linux OS, and virtualization technologies. Hanife enjoys creating content and shooting videos covering these topics.