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Comment by kazinator | Hacker News Reader

That FAQ doesn't address anything. Suppose you're in a blacklisted block. Now what? Most residential IPs are blacklisted.

When I say I'm self-hosting, I mean I have a machine under a table right here in my home: True Scotsman's cotsman's self-hosting.

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When it is blacklisted, the user/owner of the IP must go to each "anti spam" provider that blacklisted the IP. I.e. spamhaus, they have a page[1] to check if an IP is blacklisted as well as asking to remove the IP from blacklist.

[1] https://check.spamhaus.org/

Some blacklists say "this is a residential subscriber IP". Some mail servers block based on that. An IP cannot be removed from such a database.

https://www.rbl-dns.com/dul

I drop SMTP connections from servers that simply do not have matching forward and reverse DNS. This rule eliminates like 90% of spam. It's a good rule and I won't make any exceptions. There's no way to contact me. Your bounce message tells you what you have to do: get your DNS ducks in a row.

... and that's nearly impossible if you're on a residential connection and hence have no control over your reverse DNS... And who wants their mail server to self-identify as d203-0-113-5.res.fubar.isp.net ?

That's assuming your residential ISP even bothers to assign a generic PTR record to your IP.

Yep, this did not work. I tried for several years. The only thing that worked was manually filling out the required forms. Not sure if it changed lately. Out of the self host mail business for some years.

> the user/owner of the IP must go to each "anti spam" provider that blacklisted the IP.

Even that doesn't work all the time. hotmail is currently bouncing emails from me[0] even though Microsoft's own sender reputation thing[1] says my IP is in good standing.

[0] with a link to [1] just to rub it in.

What finally forced me to switch to a 3rd party for SMTP (outgoing) was a blocklist (UCEPROTECT I think) that required you to pay to be removed and my mother-in-law's email provider (AT&T) used it. My wife couldn't email her mom which was a no-go.

You can still do that by tunneling the IP address of a cheap VPS to your home network

Blacklisted residential IPs add 0.1 in the default spam assassin config

Spam from residential IP's should never reach SpamAssassin. The mail server should be rejecting the SMTP connection. SpamAssassin is something which deals with mail that has been accepted by a server: i.e. delivered. It shouldn't need to have any rules about residential IPs; what's the point.

Residential IPs are spammy, so if for some reason you've decided you're going to let SpamAssassin to handle them post-delivery, it would make sense to give them a high score.

> Spam from residential IP's should never reach SpamAssassin.

If the residential IP is in the MX record for the domain, even more so if the domain passes DKIM, why not?

That's an interesting heuristic. Given a host connecting from an apparent dynamic IP without matching forward and reverse DNS, we could take their purported e-mail domain (from where? SMTP hello? Or domain part of MAIL from?) and fetch the MX record to see if it points to that same IP address and use that as a whitelist criterion against being dropped as a residential IP. (On the hypothesis that they are trying to run an earnest self-hosted mail setup.)

However, if the host passes this check, and all other tests such that we decide to accept the mail for delivery (to be further processed by SpamAssassin), at that point why would we want to apply any score in SpamAssassin regarding the residential IP. We already decided to pass it.

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