Look I'm don't want to argue the fine points of this. Maillists seem to be able to function with this sort of checking without spammers getting in. So I would say that the mail headers are the key to this.

Actually, mailing lists only do crude checking, and are open to abuse. Normally they work surprisingly well, but it's really more by luck than management. Normal spammers don't go to the effort of faking a sender's address, but they could do if they wanted to. However, a malicious user could fake an email address and send a message that pretends to be from one person, when it's really from another. I've been on several lists where this has happened.

In fact, someone who knows a lot about email can usually get a good idea whether the sender is legitimate, but it can be a bit time consuming (doing WHOIS lookups on IP registries etc) to protect the reputation of the wronged list user, but it's not something that mailing list software generally does automatically (it's quite hard to do reliably)

In reply to Re: Re: Re: Re: Re: Re: (OT) Fighting spam by Paul Smith
in thread (OT) Fighting spam by Aristotle

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