well Mattk, maybe it should, but in reality it doesn't happen. Some providers won't give you one at all, according to watchdog the other night, you won't get one from Sky without going to court.
Coldicote, just a thought, I remeber seeing your question earlier about being recognised as a spammer. Why not set up a gmail address and use that one to send out your mail. You get a free smtp server with gmail so I don't see why this wouldn't work for you.
Alternatively I suppose you could use Neighbourhood Watch funds to set up your own domain and then you'd have complete control over everything. Your domain could be alog the lines of "AccaciaAvenue.com" or similar perhaps