Published: July 16, 2012
Indicates whether the transport provider has received one or more inbound messages.
The MAPI spooler periodically calls the IXPLogon::Poll method if the transport provider indicates it must be polled for new messages, which the provider does by passing the LOGON_SP_POLL flag to the call to the IXPProvider::TransportLogon method at the beginning of a session. If the transport provider indicates in response to the Poll call that there are one or more inbound messages available for it to process, the MAPI spooler calls the IXPLogon::StartMessage method to allow the provider to process the first inbound message. The transport provider indicates inbound messages by setting the value in the lpulIncoming parameter to a nonzero value.