gemacht:
<form action="//xyz.mail2many.de/register.php" method="post" accept-charset="UTF-8">

    <label for="input_email">E-Mail:</label><input type="text" name="email" id="input_email" value="" /><br />

    <label for="genderLine">Anrede:</label>
    <input type="radio" name="genderId" id="genderId2" value="herr">&nbsp;<label for="genderId2">Herr</label>&nbsp;&nbsp;&nbsp;
    <input type="radio" name="genderId" id="genderId3" value="frau">&nbsp;<label for="genderId3">Frau</label>&nbsp;&nbsp;&nbsp;
    <input type="radio" name="genderId" id="genderId4" value="firma">&nbsp;
    <label for="genderId4">Firma</label><br />

    <label for="input_title">Titel:</label><input type="text" name="title" id="input_title" value="" /><br />

    <label for="input_firstname">Vorname:</label><input type="text" name="firstname" id="input_firstname" value="" /><br />

    <label for="input_lastname">Nachname:</label><input type="text" name="lastname" id="input_lastname" value="" /><br />

    <label for="input_birthday">Geburtstag:</label><input type="text" name="birthday" id="input_birthday" value="" /><br />

    <input type="radio" name="datenschutz" id="datenschutz" value="accept">&nbsp;<label for="datenschutz">Ich habe die Datenschutzerklärung gelesen und akzeptiere diese.</label>

    <input type="hidden" name="m2m_code" value="flöhjsdöfjöj" />

    <input type="submit" value="Abschicken" />
</form>