How about blacklisting Gmail? They're a major source of spam.
For instance, for starters, go search through all of your email for any email sent from Google servers where the "Reply to:" doesn't match the "Mail from:", and tell me if there are any legitimate instances. We could all benefit by starting to reject all Google sourced email with a different "Reply to:".
What we really need is a blocklist / allowlist system which tracks the millions of Gmail email addresses. Has it never been seen before? Reject it with a message telling them to go sign up for the allowlist. Has it been around for a while? Allow it.
Google can't be asked to keep their own spam in check. We have to force it on them.
This is not outside of the realm of possible. Google does nothing to stop spammers, makes up their own non-public rules and doesn't communicate with the Internet community, so Gmail addresses are already on shaky grounds. For instance, for starters, go search through all of your email for any email sent from Google servers where the "Reply to:" doesn't match the "Mail from:", and tell me if there are any legitimate instances.
Why is this scenario a red flag in all instances? Mailing lists, including Google Groups, may have settings that set the Reply To to be different from the Mail From.
Lesser evil criminals such as spammers already have a supply chain of phone numbers, residential IP addresses, etc that can be used to work around the restrictions.
Of course if you do it constantly or from third-world IP addresses, I understand they refuse your attempts.
Yes. Very common. Sorry but you have a very limited view of realistic mail traffic.
While Gmail might be a major source of SPAM, they're also the email service most people legitimately use. If you block dummy-address@my-email-relay.tld, someone might be annoyed, but can sign up with their non-proxied address. If you block Gmail, the person can't just use their "real" address. You're forcing them to create a different email address to use your service - and there's no reason to think that new email address will be from a service that better validates their users.
That was once true of Yahoo, Myspace, and even AOL.
You (martenson) are one of them. The other member (di), who is a "core maintainer" of the project according to the README changelog,[2] is also a member of the Google organization on GitHub.[3] di describes himself as part of the "@google open source security team"[3] and the website linked from his profile says that he is "a Developer Advocate at Google".[4]
[1] https://github.com/orgs/disposable-email-domains/people
[2] https://github.com/disposable-email-domains/disposable-email...