Many sign up forms disallow the use of '+' in email addresses, either to prevent this, or more likely because the programmer wasn't aware it was a valid character for an email address in the first place.
If you're not going to verify that the email address they're giving you is real, why restrict them to your idea of what goes in an address? I often fill in my email address as fake@fake.fake . It's pretty easy to see that that's invalid -- to the best of my knowledge, there is no .fake TLD, and there certainly wasn't when I started doing it. But, I've never seen a form reject it.
You validate email addresses by sending confirmation emails. What's the thinking behind pretending you're doing it in the form?
You validate email addresses by sending confirmation emails. What's the thinking behind pretending you're doing it in the form?