In the realm of email servers, security is paramount. One crucial aspect of maintaining a secure mail server is controlling who can receive emails. In this guide, we’ll explore how to implement recipient restrictions and domain controls using Postfix, a popular mail transfer agent.
Why Restrict Recipients?
Limiting recipient email addresses and domains helps prevent unauthorized usage of your mail server. It adds an extra layer of security, reduces the risk of spam, and ensures that your email resources are utilized efficiently.
Step 1: Installing Postfix
If you haven’t already set up Postfix on your server, the first step is to install it. Depending on your operating system, you can use package managers like apt or yum to install Postfix.
Step 2: Configuring Postfix
Once Postfix is installed, navigate to its configuration file, usually located at /etc/postfix/main.cf. Open the file in a text editor and add or modify the following parameters:
smtpd_recipient_restrictions = check_recipient_access hash:/etc/postfix/recipient_access
Step 3: Creating the Recipient Access File
Now, create a file named recipient_access in the /etc/postfix/ directory. In this file, you can specify the email addresses or domains you want to allow or deny. Use the following format:
restricted@example.org REJECT @restrictthedomain.com REJECT
Save the file and run the following command to create the hash database:
postmap /etc/postfix/recipient_access
service postfix reload