I have been thinking about confirmation emails today and cant think of a single reason to actually send them. They are annoying and must have a user drop off rate. I know I personally don't return to some low priority sites if I'm to lazy to load my email or it takes more then 20 seconds to get the email.
What is the point and why hasn't this practice died yet? Are there any benefits I'm overlooking here?
And after they have submitted their details (which should only be critical information — seriously, nobody likes long forms.), don't send them to a dedicated "Thanks for registering" page, its a waste of time for them for them, just take them to the homepage or where ever the magic happens, and present a banner above the content thanking them and giving any info they may need.
And overall, don't get too defensive on spammers; Lets face it, your not going to get much spam until your site is popular — so go easy and don't frustrate your users, and then tighten your defenses later down the line if required.
Those are my post-signup "rules". I love working out how not to annoy users even slightly — sadly a lot of sites don't do it very well! :)