Editing Introduction to a Self Managed Life: a 13 hour & 28 minute presentation by FUTO software (section)

=== Port 25 (SMTP) ===

* '''Why it is open to everyone''': Port 25 is used for server-to-server email transmission, which means email servers from around the world need to be able to reach your Mailcow server to deliver incoming mail. Since this is a very important function for your mail server, it makes sense to allow traffic on port 25 from any source.
* '''Security concerns''': Since port 25 is open to the world, it can be targeted by spammers or malicious actors trying to exploit the service. However, this is mitigated by using tools such as <code>fail2ban</code>, <code>rspamd</code>, and strong SMTP authentication policies to detect and block abuse.

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