#infrastructure

Tagged: infrastructure

13 Jun 2026Sam wallness

SMTP Ports Explained: 25, 465, 587, and 2525

Choosing the wrong SMTP port can mean unencrypted connections, silent ISP blocks, or refused submissions. This guide explains ports 25, 465, 587, and 2525—what each does and when to use it.

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Why Your Sending IP Needs a Reverse DNS Record (And How to Set One Up)

SMTP & Infrastructure

13 Jun 2026Sam wallness

Why Your Sending IP Needs a Reverse DNS Record (And How to Set One Up)

A missing PTR record triggers Outlook to reject your mail with a 550 error. This guide explains what reverse DNS is, why mailbox providers check it, and how to configure forward-confirmed reverse DNS for your sending IP.

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