NULL. On input to the cmc_look_up function, the recipient_in parameter contains the recipient about which the message service is being queried. If there is more than one recipient passed in recipient_in, cmc_look_up only looks at the first recipient.
extension_flags
All flags used with the CMC_extension structure are valid. No further flags are defined.
Output Usage
item_data
Bitmask of extension flags. The following flags can be set:
CMC_X_COM_DEFER
The service provider will accept the message but defer it until a transport provider is ready.
CMC_X_COM_NOT_READY
No transport provider is available for the specified recipient type.