index.js
function smtpAddDomain(callback, email) {
    if ((email===undefined)||(!email.length)){
        return callback(returnError('Empty email'));
    }
    var data = {
        email: email
    }
    sendRequest( 'smtp/domains', 'POST', data, true, callback );
}
function smtpAddDomain(callback, email) {
    if ((email===undefined)||(!email.length)){
        return callback(returnError('Empty email'));
    }
    var data = {
        email: email
    }
    sendRequest( 'smtp/domains', 'POST', data, true, callback );
}
SMTP: add new domain

@param callback
@param email