easydigitaldownloads/Easy-Digital-Downloads — pull request #1128 by studioromeo (2013-04-25 19:52:20+00:00)
Title: Adds header filters on test & receipt mail functions

Adds filters on the mail headers variable on payment receipt & admin test functions.
This is so other plugins can hook in and edit the headers to pass additional data along.

First use of these filters are from [this plugin](https://github.com/studioromeo/edd-bcc).