If the ISP blocks port 25, then the ISP is taking responsibility for delivering all email sent by a user, and they have to start applying rate
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 - -- Simon Waters <simonw@zynet.net> wrote: limits. Otherwise if they send all email from their users, all they've done is take the spam, and mix it in with the legitimate email, making spam filtering harder.
Okay, I can understand why an ISP might want to apply SMTP rate-limits, but to clarify, I'm assuming you meant that ISPs (if they do block tcp/25 outbound to anything other than their own MTAs) need to watch for excessive SMTP utilization, which might indicate a spammer-client (?). ...as opposed to arbitrary SMTP rate-limits. Yes? - - ferg -----BEGIN PGP SIGNATURE----- Version: PGP Desktop 9.6.3 (Build 3017) wj8DBQFIwO90q1pz9mNUZTMRAneaAJwMgmIz99bPUYJ2HgUD6Zs1MOFXgQCgmsPY eUtV2bBKymWfxNwNOgWfp5w= =bdk+ -----END PGP SIGNATURE----- -- "Fergie", a.k.a. Paul Ferguson Engineering Architecture for the Internet fergdawg(at)netzero.net ferg's tech blog: http://fergdawg.blogspot.com/