SMTP syntax errors

[fanf]

Phil Chambers complains about non-ASCII junk in SMTP envelopes:
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050718/msg00029.html

I note that another common syntax error is to put a space between : and < and talk about building support into Exim to deal with this misbehaviour:
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00102.html

More followups discussing ways of configuring existing versions of Exim to do this, and the wiseness thereof:
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00141.html
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00147.html
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00169.html

(I also note that Exim is already strict in this manner about HELO domains.)

[update]
Using $smtp_command_argument to implement :< strictness:
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00184.html
http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20050725/msg00191.html

Comments

[knell.livejournal.com]

I'm definitely in the camp (as in, those who have to field the user complaints from people who can't get mail through) who think that that sort of anal-retentiveness is pointlessly stupid, and serves only to let people willy-wave about having memorised the whole of RFC2821.

The Internet works through concensus, and given that I've been a mail admin for many years and never known (or, really, cared) that a space between : and < is a trivial and uninteresting violation of [2]821, trying to enforce that sort of thing by bouncing mail can serve only to decrease the universe's average karma level. It doesn't seem to cause much hassle, so why bother?

[fanf]

why bother?

Because it's a much cheaper way of identifying and rejecting malware than full-on content scanning.