ListMessenger is a free mailing list management program written in PHP using a mySQL database. The program files can be downloaded from http://scripts.digitalorphans.org/listmessenger/index.php. When ListMessenger is installed on the same server as AShop and the $listmessengerpath is set in admin/config.inc.php, each product can be associated with a ListMessenger mailing list group.
If the correct path to the ListMessenger directory is set in admin/config.inc.php, a drop down list will appear on the add product and edit product pages where you can set the mailing list group. When someone buys the product, they will automatically be added to the corresponding group within ListMessenger.
The following lines must be set in admin/config.inc.php
// ListMessenger integration
$listmessengerpath = "/path/to/listmessenger";