Rails plugin which validates email address using smtp
Ruby
Latest commit f489fe8 Jan 19, 2009 Tero Tilus tune readme

README

= ValidatesEmailWithSmtp

Email validation using SMTP.

ValidatesEmailWithSmtp provides a method to validate email address
field against the mail server, which would receive the mail in case
you wanted to send one.  The original idea was shamelessly ripped from
Webdigi blog entry <em>How to check if an email address exists without
sending an email?</em>.
<http://www.webdigi.co.uk/blog/2009/how-to-check-if-an-email-address-exists-without-sending-an-email/>

Validation actually almost sends mail.  It finds out the mail server
for the domain part of validated address, connects to server and
proceeds to sending mail up untill it finds out what the server has to
say about the recipient address.  Then it quits the connection.