> Hopefully that's not the SMTP syntax you're actually using.

I typed it out live. I'm not an SMTP client and I don't have the RFCs memorized.

> I'd reject (give you a 5xx) that from my mail server for those reasons alone.

Postfix accepts it. I haven't checked the RFC to verify your concerns, but assuming they're correct, then my expectation is that postfix is liberal in what it accepts because A) it's a good idea, and B) a real mail transfer agent probably ignored those two minimal rules at some point in the past.

Postfix (and the other big receivers) will ignore it, but will send using the proper RFCs. It's still a good sign of a badly written bulk mail engine, and worth rejecting for.

> It's still a good sign of a badly written bulk mail engine, and worth rejecting for.

No, it might be worth scoring the e-mail with a spam filter, but the MTA shouldn't be overzealously throwing away e-mail.

My MTA doesn't "throw away" email. It sends back a 5xx with an appropriate message that the sending end isn't RFC compliant. Absolutely nothing wrong with that - if it's a legit sender they know I didn't get the mail.

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.

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.

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