handling spam from gmail.

[Andreas Born]

Am 11.06.2020 um 19:15 schrieb Ralph Seichter:
> Generating backscatter is definitely not a good move, and it is even
> prone to punish yourself. Better to reject the offending message with
> a 5xx status code and some explanatory text or the URL.
> 
> The various tests required to come to a decision about accepting or
> rejecting the message can be executed in a milter. Milter-regex, for
> example, is lightweight but still powerful enough to perform tests on
> combinations of various headers and the body content. Beyond that, a
> custom milter is always an option.

...and the body content...

There exists one problem: at this stage of mail reception you have no 
body content nor header information on which a milter may perform deeper 
analysis, only envelope data. The SMTP specs itself allow failure codes 
after any command, even a 5xx after the DATA command. Hoever, many MTAs 
still ignore error response codes after DATA and take the mail as sent, 
so that most mail servers will perform any error indication before DATA, 
at latest after RCPT TO. So the server has to accept mail first before 
it can scan its header and/or body, and would send out DSNs on rejection 
at this stage, probably causing backscatter as well.

I don't understand why this problem of ignoring data response codes even 
exists. It would be so much more practible to reject spam immediately 
after the body was scanned, i.e. after the DATA command, than to send 
out these DSNs.

Or does this issue no longer exist these days?

/andreas