Sure, these are basic things that are generally used as strong signals, but all this does is filter out the incompetent spammers. If you're sending from yahoo or from gmail, you've already solved the reputation problem. And there are other ways of doing the same.
> If 10000 yahoo accounts are sending spam emails, then that's a Yahoo problem. Yes, I would refuse to accept incoming mail from @yahoo.com until they've fixed their complicity.
I'd expect that this is approximately the baseline number of yahoo accounts sending spam when they aren't being actively targeted. Its less than 1% of 1% of the active monthly accounts on yahoo. So you'd like to just block yahoo constantly?
> I disagree about not knowing that they do.
Sure they know, in the sense that I also know that there are always people spamming from every major ISP. That doesn't mean that they can immediately address things. And while you're busy blocking all comcast users from sending your users email, your users are busy moving to a different email provider that identifies individual spam senders so that they can still receive legitimate email.
In closing, a simple question: if solving spam is this straightforward, why hasn't an upstart competitor (yahoo, protonmail, etc.) taken advantage of this strategy to fix the spam problem? It appears you're presuming a centralized system, which defeats the point of email and significantly simplifies the problem.
If my mail server is banning mail from Yahoo, I can't communicate with my grandparents and I stop using that mail server. Enough people do that and the mail server has no users.
inetknght, I get the sense that you run a mail server of your own. Have you taken your own advice here and blocked @yahoo.com incoming? Is it inconvenient? Is it more inconvenient than the two-step process of setting up a Gmail account?
Why are your grandparents using Yahoo instead of your mail server?
> Have you taken your own advice here and blocked @yahoo.com incoming? Is it inconvenient? Is it more inconvenient than the two-step process of setting up a Gmail account?
I haven't had any correspondence from anyone who uses @yahoo.com. Or, if I have, they haven't complained about me not receiving their email. Or, if they have, their complaint was also not received in which case it doesn't exactly matter. If it did matter then I would address it then. And, importantly, it also means there's another (less noisy) communication medium available already.
Because internet systems are one part technology and one part social. My grandparents already have Yahoo accounts and are unwilling to change that.
And if your solution to interoperating with Yahoo servers is "I don't have anyone to talk to using Yahoo servers," then I'm afraid it sounds like you're trying to solve a problem other than the one email is designed to solve.
Authentic in terms of DNS. That means using and enforcing DKIM at the minimum.
Also in terms of from: and reply-to: addresses matching each other.
> If 10000 yahoo accounts are sending spam emails to other websites, what do you do? Block all yahoo senders? Try to block the yahoo accounts as they appear?
If 10000 yahoo accounts are sending spam emails, then that's a Yahoo problem. Yes, I would refuse to accept incoming mail from @yahoo.com until they've fixed their complicity.
> All major ISPs host spammers. Often they don't know that they do.
I disagree about not knowing that they do. ISPs must respond to fraud and abuse reports or they would lose the ability to do business. ISPs not responding to spam reports are offloading the cost of policing their users onto you.