Hi Mik_1955,
Thank you for posting MSDN forum.
As far as I know when you use the
MAPI_NEW_SESSION
rum as flag, you also need to set MAPI_LOGON_UI as flag, or the function will fail.
If neither MAPI_DIALOG nor MAPI_DIALOG_MODELESS is set, at least one recipient must be specified.
Since your issue is related to outlook simple MAPI, You can post the issue
on the forum. I will move the case to off-topic.
Best Regards,
Hart
Please remember to click "Mark as Answer" the responses that resolved your issue, and to click "Unmark as Answer" if not. This can be beneficial to other community members reading this thread. If you have any compliments or complaints
to MSDN Support, feel free to contact MSDNFSF@microsoft.com.