Hi totalnet,
I do not found there is a field in MFCMAPI can achieve your requirement, however, you can try to use message tracking to find out what you want.
Please refer to the following article to understand message tracking:
Message tracking
In Microsoft Exchange Server 2013, the message tracking log is a detailed record of all message activity as messages are transferred to and from the Transport service on Mailbox servers, mailboxes on Mailbox servers, and Edge Transport servers. You can use
message tracking logs for message forensics, mail flow analysis, reporting, and troubleshooting.
Best regards,