I'm writing an email client application that communicates with an Exchange 2010 server via IMAP.
According to the IMAP spec, the server "should not" change the UID of a message between sessions. It seems to me though that Exchange does exactly that: it will often reassign a message a new (higher) UID even after the message has been fetched
by the client.
This effectively means that it is impossible to achieve any kind of exact synchronization between a client and the server.
Is this behaviour intentional in Exchange 2010? If so, why? Is the behaviour the same in Exchange 2013? Is there any way to avoid it?
See also [this StackOverflow question](http://stackoverflow.com/questions/22611608/identifying-mails-between-an-imap-server-and-a-client-application)