Re: People forging their From: addresses

[Piet Beertema <]

    For a while, I tried returning a 500 code, but I found that
    the DNS is flaky enough to actually provide false answers now
    and then, so I ended up rejecting a few messages a day who
    were otherwise perfectly legal (out of like oh 100k per day).
    So we switched back to 400 replies, so now the occasional mail
    gets delayed a bit because it gets an "unfair" 400 reply, but
    that's better than rejecting that mail altogether. Spammers
    will usually not retry even with 400 style replies when
    they're sending directly, and relays stop after a few days...
    it's bearable.
The latter remains to be seen. Originally I used 400,
but I found that it only led to massive and almost
endless retries for obviously bogus domains. Then I
switched to 500. And the loggings show that really
existing domains are hit only very rarely.


	Piet