static-chaos.net — This code doesn't just check if they entered correct formatting for their email address. This actually tests whether the email address in question actualy exists by sending a sort of "test mail" to the servers, but then canceling the message before it is fully sent.
Oct 22, 2007 View in Crawl 4
angusmOct 22, 2007
A lot of work went into this, but it's of limited usefulness. It doesn't "check that an address exists". What it does is to open an SMTP session and send an RCPT command with the desired address, then send a QUIT command before actually sending any data. If the address doesn't exist, some SMTP servers will indeed throw an error after the RCPT command. But some will issue an OK anyway and bounce a failing message later. Others may have a catch-all address set up to direct any mail to unknown addresses to /dev/null; the server will return an OK to the RCPT command, but any mail sent will just be deleted. An 'OK' response to an RCPT command is not a reliable indicator that an address actually exists.
dprophitApr 18, 2008
Site link is dead