[NCLUG] sendmail -bv

[Michael Dwyer]

> I'm trying to verify email addresses and have been using
> sendmail -bv but just found out that if the domain doesn't exist,

I belive that -bv just runs it through the rewriting engine -- that is,
it makes sure the the address syntax is valid.  Other than that, the
only reasonable way to check if an E-mail address is valid is to send
mail to it.  Even then, you won't know for sure if it bounces for about
a week...

That said, there are some intermediate tests you can do:

Run everything after the @ through DNS to see if a valid MX record comes
up.
Hit that machine pointed to by the MX and try VRFY foo at nclug.org
commands.  Mind you, a fair number of servers don't allow VRFY (or EXPN)
anymore.  Qmail puts it rather neatly. "Just send a message.  I'll try
my best!"

There are some good regexp strings in the online man pages at php.net
for testing the syntax validity of addresses without the overhead of
sendmail...