From: Phrogz <phrogz@...>
Date: 2008-02-01T03:55:01+09:00
Subject: Re: validate email address?

On Jan 31, 10:12 am, Dominik Honnef <domini...@gmx.net> wrote:
> On [Fri, 01.02.2008 01:14], Eric H. wrote:
>
> > Anyone have a code snippet that tells whether an email address is
> > "valid" but not necessarily whether it is a working address because that
> > much I can sort out through my mail server through any bounces.
>
> > I have a database of addresses where the person entering the data has a
> > bad, bad, bad, BAD habit of not validating them before entering them and
> > so I get things like "***DO NOT SHARE DATA***" and "lmnopaol.com" and
> > the like. It's not my company or else she'd be going over all the
> > entries by hand.
>
> > Thanks in advance
>
> email = "em...@host.tld"
> email2 = "email@h...@ost.tld"
>
> email =~ /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i
> #=> true/0
> email2 =~ /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i
> #=> nil/false

One of my email addresses is:
  !@phrogz.net
This is completely valid, and not even very crazy. The proliferation
of half-assed regular expressions like the above prevents me from
using that address on lots of web sites.

You cannot EXACTLY validate the syntax of an email address using only
regular expressions. You can get close, but you need a much better
regexp than the above.

Here are some more syntactically valid email addresses:
  "Me Here"@phrogz.net
  phrogz@[69.46.18.236]
  phrogz@(go)[69.46.18.236](me(yeah))