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Re: Greylisting pitfalls (was Re: 2821bis consideration - New 2nd attempt Retry Strategy recommendation)

2007-11-17 08:56:14

David F. Skoll wrote:

[Aside: I think "General Ledger" when I see GL... but anyway...]

Hi David,

If this was accounting forum, I would too. :-)

We already use BL as in RBL for Relay Black List, so why not GL for Grey List? Maybe RGL is a better acroymn?

Tempfailing RCPT commands will cause interoperability problems with certain
broken SMTP implementations, specifically ones from Lotus.  Here's what
happens.  S is the server doing greylisting and C is the broken Lotus client:

S: 220 ESMTP
S: 250 Hello
C: MAIL FROM:<bob(_at_)example(_dot_)net>
S: 250 Go ahead
C: RCPT TO:<jane(_at_)example(_dot_)com>
S: 451 Greylisting in effect, try again later
C: RCPT TO:<bill(_at_)example(_dot_)com>
S: 451 Greylisting in effect, try again later
S: 503 Need valid recipient first

at which point generates a non-delivery notification.

Sad, isn't it?

Looks like it.  But this isn't a GL issue, right?

Is Lotus Notes not understanding 451? I mean, would it behave the same thing happen with 450?

Is Lotus Notes pipelining without permission?

Should a receiver who issues a temporary 45x at RCPT stick with the 45x at DATA to avoid issues with pipeling clients using the final code? I guess not, if the reeciver did not advertise EHLO support for pipelining.


Hector Santos, CTO

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