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by 7kay 2039 days ago
I run my own mail server and have never experienced such issues. The important thing is that your mail server is not an open relay and you set up DKIM and SPF. Oh, and never run a mail server with an ip originating in a residential area, you'll get blacklisted almost instantly by virtually any mail provider.
3 comments

It isn't even necessarily 'residential' IP's. It's IP's that don't have a valid reverse dns, preferably one that is also forward resolvable. Most ISP's won't let you set your reverse DNS on 'residential' connections, so it ends up being a blocker. Now you could set up a vpn tunnel to a vps provider that lets you set your reverse dns, and then things get a bit easier.

So prereqs - 1) Valid reverse DNS on your sending IP. Preferably with a hostname that is also forward resolvable. 2) SPF Records 3) DKIM

You're right, that's the basic ingredient #1 I forgot to mention. Functional rDNS is essential. You don't want to have your mail server running at home anyhow. A friend of mine had a janky setup at home until I convinced him it's a bad idea.
> You don't want to have your mail server running at home anyhow

I do in fact want this. It may not be possible, but I definitely want it to be.

Anecdotally, I have a valid reverse DNS on my home ISP-provided static IP, and when I tried setting up a mail server I got blacklisted on the spot.

(I eventually went with a Tutanota account, fwiw)

These anecdotes are heartwarming but in the end useless as advice. If your mail is getting through it only means that there are no spammers on your network, i.e. you are lucky. Having an abusive mailer on your network (IP subnet, ASN, or even sharing your registrar) could happen at any time, with unknown impact to your IP reputation and deliverability of your mail.
I feel there is a lot of fear mongering around deliverability of emails all over the Internet which is helping the big companies to centralise a thing like email.

I have had my own email server sending emails which were not marked as spam. also I have had cases where email from Gmail addresses/ips would be actually spam.

I urge everyone to start using their own mail servers so the ecosystem around self hosting emails becomes super smooth.

why do receivers still rely on ip addresses when we have dkim and spf?

If it wasn't an effective feature for classifying spam, then people wouldn't use it. But, in reality, it's incredibly effective because the only people who want to use residential IPs and rent-a-server IPs for running mailers are criminals and a much smaller population of dorks.
I agree lists are definitely effective but its a cat and mouse game sort of with a lot of overhead. We can still use ip lists for accepting/rejecting mail but that should be the lowest priority check with very less weight.

Lists are like the DRM kind of tech, where the genuine user has the real headaches (pay a service to filter my mail, cant self host etc) while the spams are still flowing through.

T-mobile also requires that you match your forward and reverse DNS and run a webserver with a posting address on the domain in order to whitelist your mail server.