OL2000: Outlook 2000 Uses 100 Percent of the Processor When the AutoArchive Dialog Box Is Active (306855)

CAUSE

This behavior occurs in both a stand-alone client and in a Terminal Server environment.

This behavior occurs because the MAPI architecture that is included with Outlook 2000, and older clients, uses a background thread that posts messages to the idle window to prompt the idle process because a 16-bit code cannot use the SetTimer function.

The background thread is architected so that it posts another message to the idle window if the idle processing has not occurred since the thread last woke up and posted the message. The AutoArchive feature runs through MAPI's idle routine, and it blocks the idle processing from completing any other tasks while the AutoArchive dialog box appears. Posted messages pile up and cause the idle processing to keep waking up without actually accomplishing anything.

In Microsoft Outlook 2002, the MAPI was re-architected, all the 16-bit specific code was trimmed, the background thread was removed, and now relies on the SetTimer function. The SetTimer function sends one message for each timer event, and messages do not pile up as they did on the background thread in Outlook 2000.