$mail_regex =
q{(?:[^(\040)<>@,;:".\\\\\[\]\000-\037\x80-\xff]+(?![^(\040)<>@,;:".\\\\} .
q{\[\]\000-\037\x80-\xff])|"[^\\\\\x80-\xff\n\015"]*(?:\\\\[^\x80-\xff][} .
q{^\\\\\x80-\xff\n\015"]*)*")(?:\.(?:[^(\040)<>@,;:".\\\\\[\]\000-\037\x} .
q{80-\xff]+(?![^(\040)<>@,;:".\\\\\[\]\000-\037\x80-\xff])|"[^\\\\\x80-} .
q{\xff\n\015"]*(?:\\\\[^\x80-\xff][^\\\\\x80-\xff\n\015"]*)*"))*@(?:[^(} .
q{\040)<>@,;:".\\\\\[\]\000-\037\x80-\xff]+(?![^(\040)<>@,;:".\\\\\[\]\0} .
q{00-\037\x80-\xff])|\[(?:[^\\\\\x80-\xff\n\015\[\]]|\\\\[^\x80-\xff])*} .
q{\])(?:\.(?:[^(\040)<>@,;:".\\\\\[\]\000-\037\x80-\xff]+(?![^(\040)<>@,} .
q{;:".\\\\\[\]\000-\037\x80-\xff])|\[(?:[^\\\\\x80-\xff\n\015\[\]]|\\\\[} .
q{^\x80-\xff])*\]))*};

if ($email !~ /^$mail_regex$/o) {
print "不正なメールアドレスです\n";
}