I need to link to an authorization form that customers need to download within the body text of the invoice email.

Links get changed to relative URLs by the time they get to the customer inbox, making the file path unreachable.

I've set my WYSIWYG editor (TinyMCE) to default to absolute URLs, and have double checked the Invoice Email within VMinvoice. They are definitely absolute (http:sitename.com/directory/file.pdf). But they somehow get changed to relative links after being sent (directory/file.pdf).

Any ideas what might resolve this?