This would be such a handy piece of software. You could set up pre-set emails messages for your friends or workmates birthday (especially if you are on a business trip or holiday), reminders to group emails for meeting etc, set a scheduled email to your house-sitter that the garbage is due to be collected the next day, etc, etc. Another example would be if you need to send an unimportant email to someone overseas and if you sent it straight away you would probably wake them up. Or even a cooling off period for those angry emails we sometimes write. (If you set say a 3 hour delay on the send then you have that time to think about what you wrote and change/delete it if you want).
So if there is nothing out there like this come on developers, this could be the next Big Application. Your thoughts ???