It’s quite sad the only mail server out there which checks if you are allowed to use a email address is exchange. With all others you can set the from: header however you like.
Who cares whether it's the MTA that does it or a collection of daemons invoked by the MTA? Just get things configured correctly, and you should be gold.
Now as far as every other mail operator setting up their stuff right such that From spoofing is no longer feasible, well... Can't help ya there. I don't run my email to make money, so the incentive to adopt pathological configs for the sake of maximizing the number of users/Domains who can send from one IP ain't there.
Now as far as every other mail operator setting up their stuff right such that From spoofing is no longer feasible, well... Can't help ya there. I don't run my email to make money, so the incentive to adopt pathological configs for the sake of maximizing the number of users/Domains who can send from one IP ain't there.