RE: Exchange --> Greylisting

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Thank you for your workarounds. I have had the same problem with delay
notifications lost in a black hole. I noticed that when we rebooted the
server for other issues, the notification messages suddenly showed up. We
were planning to implement a regular reboot of the server, but after reading
your post, instead we will use workaround 2.

"Yizhar Hurwitz" wrote:

HI.

I had the same problem that was mentioned here before:
http://groups.google.com/group/microsoft.public.exchange.admin/browse_thread/thread/36cd5a8dabd3663d/09ff07ac14b116db

For those who doesn't know - greylisting is used on some mail servers to
tempfail first attempt of an email, asking the sending server to retry later.

In short (more details will follow) - Exchange 2003 SP2 failes to re-queue
messages sent to some servers that implement greylisting.
This does not happen all the time (some messages go through but sometimes it
fails).
When the problem happens, those emails are hidden in some kind of a black
hole, and the sender does not get an NDR nor Delay notification, even after
those timeouts expire.
Such messsages can remain "lost" for days or even weeks, until the SMTP or
Information Store service is restarted.
After a restart of SMTP service, Exchange suddenly finds those lost emails
(I guess they were in the Mailbox Store), and retries to send them or returns
NDR to the sender.

I have just openned a PSS case about this and working with Microsoft.
However this issue is not easy to re-produce, so I would like to get
feedback from you as well.

My questions to you -
Have you encountered similar problems, such as users complaining that they
got NDR for a message they sent 2 weeks before, or that the recipient calls
them and tell them "why did I got now and email you sent a week ago?"
(And you find out that the recipient server uses greylisting).

Meanwhile I have found those workarounds and currently I don't have the
problem, but it still needs further investigations:

Workaround 1: Send emails to greylisting domains via an ISP Smart Host
(using SMTP connector).

Workaround 2: Use scheduled tasks to restart SMTP service every day.

Workaround 3: Change SMTP virtual server retry timeouts (this does not seem
to help but I changed it anyway to values you can see below).


.

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