PC MAPI: How To Determine if a Mail Session Already Exists (128963)

SUMMARY

When a you use the Microsoft Mail for PC Networks Simple Messaging Application Programming Interface (Simple MAPI), you can fairly reliably determine if an Microsoft Mail for Windows session is currently established. This information is helpful due to the design of the Windows client and the inability to have multiple simultaneous logins.

When it is largely unknown to the developer if a session will currently be running, the following Microsoft Visual Basic version 3.0 code logic can be helpful in reducing login errors.

MORE INFORMATION

The following code fragment is just one example of how to optimize a successful login, without user intervention. This should be helpful for developers who want to maximize their applications ability to login successfully.

NOTE: The message box calls are merely for clarity.

Sub Form_Load ()
' ***                         ***
' *** Start sample login code ***
' ***                         ***

rc& = MAPILogon(0&, "", "", 0&, 0&, lhSession&)
If rc& <> SUCCESS_SUCCESS Then
  MsgBox "Login Error or session does not exist = " + Str(rc&)
  ' No session exists so lets pass info to create one
  rc& = MAPILogon(0&, "admin", "password", 0&, 0&, lhSession&)
  If rc& <> SUCCESS_SUCCESS Then
    MsgBox "Failure to login at all"
    End
  Else
    MsgBox "Successfully logged in as admin"
    ' Send important message
    rc& = MAPILogoff(lhSession&, 0&, 0&, 0&)
    End
  End If

Else
  MsgBox "Mail session currently established"
  ' Send important message
  rc& = MAPILogoff(lhSession&, 0&, 0&, 0&)
End If

End
End Sub
'*** end code fragment ***'