Do you think “Retype Email” in registration forms really necessary? What are the chances that we mistype our email address? I’ve a feeling it just adds annoyance for the user. I’ve seen some major sites don’t implement this like Paypal. What are your thoughts?
I can’t tell you how many times customers have sent me an angry e-mail that they haven’t received any communication from me, and it’s because they didn’t type their e-mail right when purchasing.
Since most people just copy/paste their email address from the first field to the second, having the second field there serves no purpose whatsoever.
Totally agree with ‘felgall’, that’s exactly what I do and it always annoys me when a site uses JS or similar to stop me doing this.
I think the choice is based on what you need it for. If its for log in details then if they register an incorrect address it won’t be a major problem for the user (although you’ll have an inflated unverified user base) as they can always reregister once they realise the error. If its for contact info, as ‘Dan Grossman’ said, you’ll have angry customers who don’t get a valid response.
Having a lengthy address, I just mark the first entry and pull it into the next input.
I think the better would be a clear note that a confirmation email will be sent to the address. Then they will check that the confirm is received before they get angry. 
I agree that retyping email fields is a pointless exercise as few people retype the address, they just copy from one box to the other. However getting the user to verify the account before they can continue the registration (Via sending an email with a small code attached to verify the correct account was given) would be a more useful way of preventing incorrect email listings.
As a method of validating an email address it’s only a partial solution because the user could type the wrong address in both fields?
Having a visible note to say how important getting it right is a good idea
I have my main email address stored in Opera’s Wand, so I only had to type it right once. Since then it’s just a matter of a couple of keystrokes.
I agree that the retype field is of very limited use, though.
That’s the Opera solution. Those using inferior browsers usually have to type the address once per form and then copy/paste to the second field. Of course some of the inferior browsers also don’t have an option to prevent the web page using JavaScript to block the paste as well.