Sort a List by enum where enum is out of order

An alternative to using IComparer would be to build an ordering dictionary.

var orderMap = new Dictionary<MessageType, int>() {
    { MessageType.Boo, 0 },
    { MessageType.Bar, 1 },
    { MessageType.Foo, 2 },
    { MessageType.Doo, 3 }
};

var orderedList = messageList.OrderBy(m => orderMap[m.MessageType]);