if ($entry =~ /^([a-zA-Z0-9\@_\.]*)$/) {

##</code><code>##

    if ($entry =~ /^([a-zA-Z0-9_\.\-\!\%\#]+\@[a-zA-Z0-9_\.]+)$/) {

##</code><code>##

 qw [
      abc@123.it
      a@b
      tech-support@super.net
      user_144@z.com
      webmaster@estherdyson.museum
 ];