[NCLUG] Lost mail due to graylisting!

[Bob Proulx]

Sean Reifschneider wrote:
> Stephen Warren wrote:
> > That's a bit of a bummer - it's the first (non-spam!) email I've lost 
> > due to graylisting. Guess I have to whitelist their domain or something.
> 
> You might want to contact their customer support as well, because never
> retrying on a 4xx response either means that their system is broken or it's

You are being too kind.  Not retrying on a 4xx response is definitely
broken.  Unless you really want to discard the message.

So many times users are beyond their quota, full disk, temporary DNS
failure, etcetera, etcetera.  Not retrying will lose a lot of email
regardless of greylisting.

> because of an unwise policy that they should probably consider changing.

  nc smtp1.americawest.com 25
  220 smart-smtp.awa.com ESMTP Server (Microsoft Exchange Internet Mail Service 5.5.2657.72) ready
  quit
  221 closing connection

As much as I would like to rag on MS software I think if it did not
retry then it would never deliver mail to other MS machines because
they are offline so much.  So that part is probably tested out pretty
well.  I also have a hard time believing there is a knob to turn that
would turn a 450 into a hard failure.  Does MS expose that type of
configuration?

Bob