[kolya3]

I would rather lose a few users through a faulty regexp than lose double digit percentage through an email activation step.

[gkop]

No regexp in the world will tell you if an email address is real.

[kiallmacinnes]

Of course - I doubt anyone (smart) has ever claimed that to be the case.

However, they can, if implemented correctly, tell you if the email address is syntactically valid.

[andyhmltn]

Why check it's an email at all if you're just going to presume it works?

[ianstallings]

Think about the repercussions of not using a validation email. Anyone can sign anyone else up. That's even more unacceptable IMHO.

[arkitaip]

How many emails to [e-mail] or [e-mail] are you willing to pay for (the nickels add up)? What if someone uses my email address to sign up for your service?