This can be caused by either not including an unsubscribe link in the message, or with an incorrectly formatted sender address in the TeamRaiser configuration.  To verify the sender address is correct:
  1. Select edit on the TeamRaiser.
  2. Step 3 Select Event Options.
  3. Under Related Actions, Select Edit Advanced Options.
  4. Step b Define Event Options.
  5. Go to step 7 and verify the email address is valid (no invalid symbols or characters), or the space is left blank (so it will use the site default) , or does not include a space after the email address.
If it contains a space after the email address delete the space and save the changes.  Now the email should be able to be approved.