I have a Windows Server 2003 R2 Standard 32-bit server running Service Pack 2 with Exchange Server 2003 Standard running Service Pack 2. My event logs are always being filled by event ID 9671. The error messages always say this: -- User <username> has exceeded the allowed maximum number of simultaneous registrations for MAPI notifications. The configured maximum number of event notification registrations is 50. -- Googling around a few months back I noticed everyone saying user "SYSTEM" was the one that showed up under <username> on their server. I don't ever notice "SYSTEM" erroring in my event logs as they are always actual usernames. Some of them MAY be "SYSTEM" but I have yet to see one. I edited the registry entry that others mentioned in different forums, etc. to increase the number of event notification registrations from 8 (default) to 50. That's why the error says 50 now, because I increased it. I guess now I'm at a point where there isn't any good information on this that I have found and I'm stuck as to how to stop this from happening.