Last modified: July 23, 2011

Applies to: Outlook

Gives control of the CPU to the MAPI spooler so that it can perform any tasks it considers necessary.

HRESULT SpoolerYield(
ULONG ulFlags


Reserved; must be zero.


The transport provider successfully released the CPU.


Instructs the transport provider to stop the delivery of the message to any recipients that have not yet received it.

The IMAPISupport::SpoolerYield method is implemented for transport provider support objects. Transport providers call SpoolerYield to allow the MAPI spooler to accomplish any necessary processing.

Call SpoolerYield when you are performing lengthy operations that can be paused. This allows foreground applications to run during a long operation, such as delivery to a large recipient list across a busy network.

If SpoolerYield returns with MAPI_W_CANCEL_MESSAGE, the MAPI spooler has determined that the message should no longer be sent. Return MAPI_E_USER_CANCEL to your calling process and exit, if possible.

For more information about yielding to the MAPI spooler, see Interacting with the MAPI Spooler.