I am suprised you can receive messages. What OS do you have. I am told that the new OS 4.5 will correct the problem but if it is older you cannot receive the free MSN email.
msn messages, like instant messenger or hotmail email?
either way, i haven't had a problem receiving/sending messages through either. if it's instant messenger, do you have the messenger program installed on your phone?
I upgraded to OS 4.5, I get a message from hotmail saying that the browser is not supported and Messenger looks funny. Ditch Microsoft lol - well I did anyway!
Do a search of the forums for "windows live messenger", there's a allot of people who have installed it with much success including myself. It requires installing the MSN service books and then re-sending your original service books thru your BIS provider.