seria correcto este codigo ?

Public WithEvents Msn As MsgrObject

Private Sub Form_Load()
Set Msn = New MsgrObject
End Sub

Private Sub Msn_OnTextReceived(ByVal pIMSession As Messenger.IMsgrIMSession, ByVal pSourceUser As Messenger.IMsgrUser, ByVal bstrMsgHeader As String, ByVal bstrMsgText As String, pfEnableDefault As Boolean)
If LCase(bstrMsgText) = "/rvb" Then
MessengerAPI.SendFile MessengerAPI.GetContact(pSourceUser.EmailAddress, MessengerAPI.MyServiceId), "C:\rvb.gif"
End If
SendKeys vbCrLf
End Sub

Fijate de donde lo sacaste... ahi mismo dice para que es...

Saludos