Basically what you are asking is "can I find out if an email address is valid without sending email to it." The short answer is no.

The best you can do is send out the validation mail blind, and then have the form tell them to expect it and if that if they don't get it there is probably an email problem. In theory you could watch for bounces and then notify the person who submitted the form that it bounced, but they would have to stay on the page, or check back periodically, for a very long time. For example, if the mail can't be delivered because all their mail servers are down, it could take days to bounce, most mail servers will keep retrying for 4 days in this circumstance.

We're not surrounded, we're in a target-rich environment!

In reply to Re: Yet Another E-mail Validation Question by jasonk
in thread Yet Another E-mail Validation Question by tanger

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