Admin > Configuration > E-Mail Options > Set "Contact Us" Email Dropdown List

Using this feature in 1.3.7 to set up multiple email addresses for our contact form, e.g.

Name 1 <email@address1>, Name 2 <email@address2>

Entering multiple name/address pairs with spaces after the commas (as shown in the instructions for this field) breaks the email sending, at least on our server. Removing the spaces works, or changing line 43 of includes/modules/pages/contact_us/header_php.php to add a trim():

$send_to_name = trim(preg_replace('/\<[^*]*/', '', $send_to_array[$_POST['send_to']]));