I have installed WLMD and since then my email button on Messenger opens WLMD. But I don't want to use WLMD for email and I want to see my mails in WLM in an IE. I won't delete WLMD. Don't suggest such a thing
EDIT: I have just found how to repair this. Delete this registry entry.
HKEY_LOCAL_MACHINE>Software>Microsoft>Windows Live>Communication Clients>Shared
Remove Mail Install Root key. Thanks