The MAPISendMail function supports options through its flFlags parameter. Your client application can set the following flags when sending a message.
| Flag | Description |
|---|---|
| MAPI_LOGON_UI | Allows a logon interface if required. This flag should be set if you are using an implicit session. |
| MAPI_NEW_SESSION | Prevents Simple MAPI from using an existing shared session if one is present. |
| MAPI_DIALOG | Displays a dialog box which allows the user to create a message. This flag should be set if you do not have a MapiMessage structure already constructed, or if the user is composing a message interactively. |