I've said for years that outsourcing mail services is a bad idea, especially for Web mail. Here's a crystal clear example of what can happen when you do:

David Airey, like millions of other people, decided to use Google's Gmail as his primary inbox for sensitive communications. Airey also used his gmail.com address as a contact point for his domain registration. Because he made that choice someone was able to take advantage of a flaw in Gmail to hijack his mailbox, and thus his domain and entire Web site. Then he faced a battle to get it back. Fortunately for David many people stepped in to assist.

The lessons to be learned from all this should be pretty clear...