NYCPHP Meetup

[Daniel Convissor]

On Thu, Dec 02, 2004 at 01:21:25PM -0500, James B. Wetterau Jr. wrote:
> > Daniel Convissor wrote:
> > >
> > > '^[a-z0-9_.=+-]+@([a-z0-9-]+\.)+([a-z]{2,6})$'
> 
> I feel that that regex is way underblown.
> 
> It misses many valid email addresses.  It's perfectly legitimate to
> have characters other than [a-z0-9_.=+-] in the local part of the
> address.

Back when I did a study of RFC 822, those were the characters that the 
RFC said were valid.  Perhaps I made a mistake.  But I haven't heard 
of any problems with my expression.

But RFC 822 has been replaced by 2822.  I believe the newer RFC allows 
more characters in the local part.  Again, I haven't heard of any 
complaints with it.  None the less, looking at 
ftp://ftp.rfc-editor.org/in-notes/rfc2822.txt shows the following:

atext           =       ALPHA / DIGIT / ; Any character except controls,
                        "!" / "#" /     ;  SP, and specials.
                        "$" / "%" /     ;  Used for atoms
                        "&" / "'" /
                        "*" / "+" /
                        "-" / "/" /
                        "=" / "?" /
                        "^" / "_" /
                        "`" / "{" /
                        "|" / "}" /
                        "~"

Most of those characters are quite unusual for email addresses.  

<grumble>
 fine
</grumble>

Let's "do the right thing..."  Here's a tweaking of my ereg 
expression to include all the legit characters in the local part:

'^[-!#$%&\'*+/=?^_`{|}~a-z0-9.]+@([a-z0-9-]+\.)+([a-z]{2,6})$'

The one flaw with that is it allows the local part to be just a 
period: . at foo.com.

So, while we're at it, let's take it all the way:

$expr = '^[-!#$%&\'*+/=?^_`{|}~a-z0-9]+'
      . '(.[-!#$%&\'*+/=?^_`{|}~a-z0-9]+)*'
      . '@([a-z0-9-]+\.)+([a-z]{2,6})$';

I've needed to do this for a while.  Thanks for the excuse.

--Dan

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