[anonyfuss]

At which point the legit sender does what -- replace their MtA? More likely they just contact thir receipient out-of-band (eg; gmail) and avoid your over-zealous mta.

Whether you think you're 'Throwing away' is just semantics. From a user's perspective that's exactly what you're doing.

[baudehlo]

It's my MTA, I'm the "user". My server, my rules. Just like if you want to come into my house you come in the front door and take your shoes off, not crash through the window in muddy boots.

[anonyfuss]

In that case, I wouldn't say it's a particularly useful anecdote for anyone else.