On Sun, Dec 29, 2024 at 17:25:40 +0000, mick.crane wrote: > hello > I'm not really understanding the internet. > Can I do my own SMTP server and send mail off to the right place without > having the device open to random internet connections?
Are you envisioning mail as "outgoing only", with nobody ever able to respond to you? If so, then the answer is: maybe. If your ISP doesn't block outgoing TCP port 25 connections, then you should be able to make SMTP connections to other sites, to send them your email. (If your ISP blocks this port, then the answer is: no.) However, sites that receive your connections may choose whether they're willing to accept your mail. Your mail may be considered "spam", either by virtue of its content, or by virtue of your connection metadata (how your IP address resolves to a DNS hostname, whether your IP address is part of a dynamically allocated residential block, and so on). Some sites, I've been told, may even attempt to make an SMTP connection to the registered MX host for your sender's domain, and if they can't make such a connection, they may consider your mail to be spam. Also, what good is a one-way email connection to the world? How are you going to carry on a conversation with someone if you're the only one able to send messages? That kind of sounds like the very essence of spam, doesn't it?
