Evan Dodds - Microsoft Exchange Server Blog

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Badmail changes in Exchange 2003 SP1

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Prior to Exchange 2003 SP1, if your SMTP protocol virtual server didn't have anywhere to go with a timed-out email, it would drop it in the BadMail directory on your server. This directory could potentially grow and grow without bounds until it filled up the disk, etc. There are two big changes to Badmail in the SP1 timeframe: one in SP1 directly, and one in the WebRelease “WR1”.

In the Web Release, a new script “Badmail Deletion and Archiving” was released that will aid in maintining the size and growth of this Badmail folder on your server. This will allow you to “trim” the directory down on a scheduled basis to keep the size under control.

However, even bigger is that by default in Exchange 2003 SP1 retaining undeliverable messages in the Badmail folder is now disabled and its behavior is controlled by a set of registry keys.

Set under: HKLM\System\CurrentControlSet\Services\SMTPSVC\Queuing   (note the spelling: “Queuing“)

Value: MaxBadMailFolderSize  
This is a DWORD which defaults to 0 if not set. It is the max size (in KB) that the Badmail folder can grow to before Badmail retension is stopped; thus setting it to 0 turns off the Badmail folder and prevents possible DoS attacks. Messages that would have been sent to Badmail will simply be discarded if the MaxBadMailFolderSize is set to 0. If you set this to -1 (0xFFFFFFFF in hex) it will revert to the pre-SP1 behavior of growing without bound.

Value: BadMailSyncPeriod
This is a DWORD which specifies how often we should check the size of the badmail folder (in minutes). If the BadMailSyncPeriod has not been reached, we won't rescan the directory and discover if Badmail items have been removed manually by the Admin.

Comments
  • How come none of that made it into the release notes? I dont even think it was in the SP1 webcast. It seems to be one heck on an under-documented release. It isnt even mentioned in the Badmail Archiver readme I dont think.

    But this bit is a real improvement.

    Also, I think in the above paragraphs, you are using the word Archiving in two distinct contradictory ways. The first is in relation to what Exchange has always done, ie "archive" bad messages into the BadMail directory, which you can now limit. The second is with the Badmail Deletion and Archiving” script, which is talking about "archiving" those badmails.

  • Exchange-faq.dk - Din portal til Microsoft Exchange Server information

  • I am trying to set the value to -1, per your instructions, but regedit won't let me set a negative value for a DWORD key. Using Hyena I can do it, but the value in regedit then shows as 0xffffffff (4294967295). Are you sure your instructions are correct?

    Scott.

  • These keys are not present on any of our SP1 servers, is SP1 supposed to create these keys ??

  • The Keys are not visible by default. You are able to add these keys and change the values.

  • Scott - you are correct. "-1" = hex "0xffffffff" in the Regedit GUI, so I will update the page to be more clear.

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