[wp-hackers] is_email

[Mihailo Stefanovic]

> > (?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\".\[\] 
> >  [...etc, etc, etc, etc, etc...]
> > \t])*))*\>(?:( ?:\r\n)?[ \t])*))*)?;\s*)
> 
> Wow. That just kicks ass :)
> 
> Maybe not very practical, but very ass-kicking.

I've just read in a Harry Fuecks' book "PHP Anthology" that full regular
expression, which correctly validates every possible email address, is more
than 6 KB long :)) You can find it in O'Reilly book "Mastering Regular
Expressions".