Error in Suspicious Activity Tracker

I'm getting 'returned' emails. The headers look like this:

A message that you sent contained no recipient addresses, and therefore no delivery could be attempted.

------ This is a copy of your message, including all the headers. ------

To:
Subject: Datastore plugins updated

Hello,

make sure that you have specified your email address in the tracker product settings.

I guess that would be the problem

For some reason I assumed it used the admin e-mail address.

I'm getting a constant stream of these e-mails now. It seems everytime my datastore cache is cleared I get e-mails.