This extension adds functionality to add attachments to message templates. You can add attachments to templates by editing the message templates under Administer --> Communication --> Message templates. Updating a template through the e-mail screen does not work.
Download the extension and install it through the Manage extension screen of CiviCRM. No further configuration is needed.
This extensions implements the form hooks to add upload fields to the edit message templates screen. Once a file is uploaded the file stored and linked to the message template. The file is also stored in the civicrm_file table.
When sending an e-mail this extension will check which template is used and which files belong to that template and adds them to the e-mail message.