Email Delivery for Multiple Domains with Separate Mail Servers Behind NAT: A Postfix Guide

Описание: Organizations often host multiple domains with separate mail servers behind a Network Address Translation (NAT) gateway for security and efficiency. However, this setup poses challenges for incoming and outgoing email delivery. This article presents a comprehensive guide to resolving these challenges using Postfix, a powerful and flexible mail transfer agent.

By configuring Postfix as an SMTP relay and leveraging its transport map functionality, organizations can seamlessly route incoming emails to the correct internal mail servers based on recipient domains. This ensures that emails for each domain are delivered to the right destination, even when sharing a single public IP address. Additionally, Postfix can manage outgoing emails from internal servers, overcoming NAT limitations and enabling reliable delivery to external recipients.

This guide provides step-by-step instructions on configuring Postfix for multi-domain environments, including detailed explanations of the transport map file and the use of postmap for efficient routing. It also covers additional considerations like high availability with Keepalived and security measures like TLS encryption.

By following this guide, organizations can effectively manage email delivery for multiple domains behind NAT, ensuring seamless communication while maintaining the security and resource efficiency of their network infrastructure.

https://blog.bsts.ovh/2024/06/inbound...