On Sat, Apr 20, 2002 at 08:29:12PM -0700, Ask Bjoern Hansen wrote: > Do you have other patches that we should put in? :-)
No patch, but a coworker recently told me that MTAs should now be considering an opening HELO as optional -- if the sender wants to lunge right in with a RCPT, it's permissible. I can't find an RFC confirming as much, but it does seem to be done that way by exim and sendmail. A tangentially related issue I noticed is that of direct-to-MX spammers conducting blind transmissions -- they write helo/rcpt/mail/data and the contents of the mail without regard to the error values returned, thus incurring a stream of 500 errors (and putting the spam in my maillog, since I leave tracing enabled.) Still trying to think of a good response to that one. The nearest approximation I can think of is to presume the spammer hasn't doctored or reimplemented their own TCP stack, cramp the TCP receive window size down, and if the sending host ignores a 553 on DATA in ESMTP, or on anything in SMTP mode, close or cork the socket. It might avoid transmission of some packets, or it might be a total waste of effort. -- Devin \ aqua(at)devin.com, 1024D/E9ABFCD2; http://www.devin.com Carraway \ IRC: Requiem GCS/CC/L s-:--- !a !tv C++++$ ULB+++$ O+@ P L+++
