We have published a new feature:
You can now create an “Attachment” column in your spreadsheet and add URL of files stored in Google Drive.
Yet Another Mail Merge will get those files from Drive and attach them to the emails sent.
See doc: https://goo.gl/v5F598
As a reminder, this page has been built for specific feature requests, which will help us to prioritize the implementation of new functionalities into YAMM.
Therefore, if you have any troubles using the add-on, we would kindly invite you to consult first our documentation: https://sites.google.com/site/scriptsexamples/available-web-apps/mail-merge/documentation
If you still need help, please address all your issues to our support team (email@example.com) and we will try our best to provide you assistance.