jandreasen on "[Plugin: Music Store] Not getting download email"

The great folks at Codepeople sent me the correct Notification URL, which was http://PutYourWebsiteInHere.com/?ms-action=ipn.

If you have a normal WordPress install in the root of your public_html directory, this may also work for you.

This fixed the error message I was getting from PayPal on the IPN settings page, but didn't fix the problem with not getting the email confirmation messages.

I finally deactivated 4 plugins that I wasn't using, and one of them was apparently causing a conflict, because after that, the confirmation messages started coming through. I don't know which plugin it was, but here's the list of the ones I deactivated:

Advanced Code Editor
Child Themify
List category posts
More Fields

Hope this helps!