Me breaking all the rules.

gistfile1.txt

// This function steganographically (kinda) encodes the iso language code into a gmail email address.
// dot characters are used because gmail ignores these when routing mail, but we can still write gmail filters based on them.
function langemailification($lang) {
    global $multiplexer_email; // I'm so sorry. I learned it from watching YOU.
    list($user,$host) = split('@', $multiplexer_email);

    // Break the user part of the email address into two parts: the first character, and the remainder.  Call them A and B.
    // We'll insert our dots 1) between A and B, and 2) after B.
    // Like so: A...B...@gmail.com
    list($a,$b) = array(
        substr($user,0,1),
        substr($user,1)
    );
    // Example return for $lang == 'es':
    //         langua  e  gecsrs         s         @gmail.com
    // return "l.....anguagecsrs...................@gmail.com";
    return $a . abc_to_dots($lang[0]) . $b . abc_to_dots($lang[1]) . "@$host";
}