System requirements for running Postfix

Setting up Postfix as your Mail Transfer Agent (MTA) requires a solid understanding of the system requirements to ensure optimal performance and reliability. This guide details the necessary prerequisites for installing Postfix on CentOS and Ubuntu systems, tailored for server administrators new to Postfix.

Table of Contents

• Introduction
• Hardware Requirements
• Software Requirements
• Network Requirements
• Security Requirements

Introduction

Postfix is a robust, efficient, and flexible MTA, making it an excellent choice for handling email on Linux servers. Before installation, ensuring your system meets the necessary requirements will facilitate a smooth deployment and operation.

Hardware Requirements

Postfix is designed to run on a variety of hardware configurations, from old servers to modern infrastructure:

• Processor: Minimal requirements, but a modern multi-core processor is recommended for handling high volumes of email.
• Memory: At least 1 GB of RAM for small environments, with more required for higher mail volumes.
• Storage: Minimum of 5 GB free disk space; SSDs are recommended for faster mail processing.

Software Requirements

Postfix can be installed on any modern Linux distribution, but specific packages and configurations are necessary:

• Operating System: A current version of CentOS or Ubuntu with long-term support and security updates.
• Dependencies: Required libraries and utilities like OpenSSL for TLS, Cyrus SASL for authentication, and more.

# CentOS
sudo yum install cyrus-sasl-plain openssl mailx
# Ubuntu
sudo apt install libsasl2-modules openssl mailutils

Network Requirements

Proper network setup is crucial for ensuring that your Postfix server can send and receive emails reliably:

• Hostname: A valid Fully Qualified Domain Name (FQDN) configured in the DNS.
• Firewall Settings: SMTP ports 25, 465 (SMTPS), and 587 (submission) must be open.
• Reverse DNS: Must be configured to point to your server to reduce the likelihood of your emails being marked as spam.

Security Requirements

Securing your Postfix installation is essential to protect your mail data and server:

• Secure Connections: Configure Postfix to use TLS encryption for all connections to ensure data security.
• Access Controls: Implement strict access controls and authentication mechanisms to safeguard your email system.

# Edit Postfix configuration to enforce TLS
sudo nano /etc/postfix/main.cf
# Add or modify the following lines
smtpd_tls_security_level = may
smtp_tls_security_level = may