/[A-Za-z0-9._%-]\@[A-Za-z0-9_%-.].[com]/ and say "'$_' matched"
  for 'x@zzc', 'a b c@c!c', '?@?@?e@a.m';
__END__
'x@zzc' matched
'a b c@c!c' matched
'?@?@?e@a.m' matched