Editing Futotemporarywikipage (section)

=== Rule 1: Forwarding SMTP (Port 25) – the ONLY rule you need if you are using OpenVPN to connect to your mailserver! ===

* '''Protocol''': IPv4 TCP
* '''Source''': Any
* '''Destination''': 192.168.5.3
* '''Port''': 25 (SMTP)
* '''Description''': NAT Forward Postfix SMTP to Mailcow

'''What this rule does:'''

* This rule forwards unsecured SMTP traffic on port 25 to the Mailcow server at 192.168.5.3.
* SMTP on port 25 is traditionally used for sending emails between email servers. However, it’s not encrypted by default, meaning the data can be sent in plain text.
* '''Why this is ALWAYS needed''': Although not as secure as SMTPS, port 25 is required for email delivery between servers on the internet. When your Mailcow server sends or receives emails from other email servers, it typically uses SMTP on port 25. This rule makes sure that your Mailcow server can communicate with other email servers to handle incoming and outgoing email traffic. Keeping port 25 closed means saying goodbye to receiving email. If you’re like me, this might be step 1 to solving a lot of life’s problems…

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