email subjects

So I got tired of saying Hi as the subject when I don't kow what to title it and don't want the email program to say "You dont have a subject! Are you sure you don't want to have a subject. You need a subject! Every email should have a subject!""" So I thought I would try just Hello. I wonder what email programs have against emails without subjects anyway.

I got the above paragraph from an email friend and I have to agree whole-hartedly. Why were subjects ever entered into emails. Yes I understand it helps with the spam problems, but there should be some way to elemintate them from friendly emails sent to friends and family if we don't think they are needed. Some programs will not send the email without a subject. And just how many times can you send one that says "HI". In fact my programs will sometimes put a message on that I am spamming when I have used "HI" to many times in a short length of time. I would like to know who sets up the programs for computers and just what do they put in the subject of emails to their friends. Do they even have friends? Or are computers their only friends.