Very, really very much I hate the mail without subject. Many people (even professionals) continue to send mail to anywhere, which doesn't tell me anything at first sight and is getting ordered with all other such messages (I must check if there is a bug in Bugzilla for that).
I appeal to anyone sending electronic mail - don't send messages without subject. It is the most essential thing of a message. Always put subject on the messages, which you send, if you want them to be taken into consideration.