Hotmail said the server was too busy to let me access my e-mails today.
MSN Messenger Live acts up if two people who are appearing offline are messaging each other - it starts sending the instant messages as e-mails instead.
But that's nothing in comparison to the way Yahoo Messenger has been messing me up again recently. In a conversation, some messages get though, some don't, but you're not aware of the fault. You might think the other person is ignoring you, or as happened with me, you get the wrong replies to your questions, and vice versa. Can lead to serious misunderstandings. Luckily, both sides had recorded what appeared on their screens, and sending a copy via e-mail called a halt to any hostilities. Dangerous business, though.
I'd cancel my subscription if I'd ever paid for it.
