doctrine2/manual/codes/Working with objects - Dealing with relations - Creating related records.php

<?php
// NOTE: related record have always the first letter in uppercase
$email = $user->Email;

$email->address = 'jackdaniels@drinkmore.info';

$user->save();

// alternative:

$user->Email->address = 'jackdaniels@drinkmore.info';

$user->save();
?>