|Important: Modifying the registry can be dangerous. An incorrect registry modification can destroy Windows and/or your applications. Perform a full system backup before continuing.
Please also note that Exchange Server 2003 registry strings referred to in this article are comprised of one line with no spaces.
TOP 10 MICROSOFT EXCHANGE SERVER 2003 REGISTRY HACKS
Lotus Notes URLs won't hyperlink in OWA and Exchange 2003
Disable the use of Microsoft Outlook .PST files in Exchange 2003
Optimize Exchange Server 2003 database maintenance
Modify BADMAIL behavior and reporting in Exchange 2003
Allow batch files and bulk mailings in Exchange 2003
Enable drive mapping in Exchange 2003
Configure Exchange 2003 to ignore zombie ACLs and ACEs
Enable automatic Exchange IMF updates via Microsoft Update
Troubleshoot ActiveSync error in Exchange 2003 SP1
Override OWA attachment size limit in Exchange 2003
Outlook Web Access will not recognize Lotus Notes URL links contained in Exchange 2003 email. To fix this Notes/Exchange compatibility issue:
NOTE: If you have a front-end/back-end environment, you'll need to configure this change on both the front-end and back-end Exchange servers. Also, this only works on Exchange Server 2003 SP2 or higher.
Create or modify the DWORD registry value: HKEY_LOCAL_MACHINE\Software\Microsoft\Office\11.0\Outlook\DisablePST. Set the value to 1 to disable .PST files, or 0 (default) to enable them.
Note that .PST files already located in a user's email profile will still be functional. Therefore, you should manually remove all .PST files from the profile prior to setting this value. This also includes disabling the auto-archiving feature, which takes advantage of .PST files.
The registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS
Create a REG_DWORD key named OLD Minimum RunTime (this key is case sensitive), and assign it a value that reflects the number of minutes that you want online defragmentation to run as a part of the maintenance cycle.
You can also control the amount of time that the online defragmentation process runs after the maintenance cycle completes. To do so, go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS
Assign this key a value that reflects the number of seconds for which the online defragmentation process should run. For example, a value of 3600 would cause the process to run for 3,600 seconds (i.e., one hour).
In most cases, you probably won't have to adjust the registry keys, but you should make sure that you optimize the Exchange 2003 database maintenance interval settings for each store for your particular server.
Turning on BADMAIL reporting in Exchange 2003 SP1 requires a registry edit. This also allows you to set BADMAIL behavior. To modify BADMAIL behavior, edit a DWORD setting in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SMTPSVC\Queuing.
The value to add or change, MaxBadMailFolderSize, is the maximum size in kilobytes allotted to each BADMAIL folder. Once this amount of space is exhausted in a BADMAIL folder, no more messages will be written to it.
Set this value to -1 (decimal) to allow for an unlimited folder size (i.e., the pre-SP1 behavior). Setting it to 0 (the default in SP1) will not write to the folder at all. Note that newer messages do not delete older ones; once the folder size has been reached, no new messages are written.
Exchange 2003 includes Installable File System (IFS) support for the Exchange store, but unlike Exchange 2000, it is not mapped by default to a drive letter (normally the M: drive) when Exchange is installed.
To manually re-enable the drive M mapping for Exchange 2003, edit the registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EXIFS\Parameters and add a new String value with the name DriveLetter and the value M. Choosing a different value will set the drive letter appropriately. If you remove or add the drive letter by changing or removing the DriveLetter value, the entire server must be rebooted to resynchronize.
Microsoft designed Exchange Server 2003 to co-exist with Exchange 5.5, if necessary. Unfortunately, the complexity of co-existence and the vast differences between the two versions of Exchange can create problems with access control entries (ACE) and access control lists (ACL).
One solution is to create a registry key on your Exchange servers to configure Exchange 2003 to ignore zombie ACLs and ACEs.
If you want Exchange to recognize zombies for some reason, you can either set the registry key value to 0x0 or you can delete it completely.
Microsoft issues a new version of Exchange Server's Intelligent Message Filter (IMF) approximately twice a month (generally on the first and third Wednesday).
What many Exchange administrators don't realize is that Exchange 2003 SP2 and later versions can be set up to download and install new versions of IMF automatically through the Microsoft Update website.
To troubleshoot Exchange ActiveSync error HTTP_500 in Exchange Server 2003 SP1:
To override the attachment size limit for OWA public folder posts (default attachment size limit is 1 MB) in Exchange Server 2003: