event Reading (Index as Long, Cancel as Boolean)
Fired just before reading the message.

TypeDescription
Index as Long A long expression that indicates the index of Message being read.
Cancel as Boolean A boolean expression that specifies whether the reading of the entire message is canceled.

Use the Reading event to cancel reading messages that are huge. Use the Reading event to notify your application that a new message is reading. Use the Read event to know the moment when the collection of Message objects are loaded. If a message was canceled during Reading event you have to use the Refresh method to reload the message from the server.  Use the UserData property to stores an extra data for the message.

For instance, the following sample cancels the reading of messages that exceed 2M bytes:

Private Sub ibx_Reading(ByVal Index As Long, Cancel As Boolean)
    With ibx(Index)
        Cancel = .Size > 2048000
    End With
End Sub