Photo Notification Email unsubscribe not working

[creativepart]

I have a user that has subscribed to my photopost install. But since I get dozens of new photos a day uploaded to that install he's getting dozens of emails a day. A problem he didn't anticipate.

I've never used the subscribe link, but he says there is a link in the email to unsubscribe but when he clicks on it he gets the following error:

"Script call malformed. Notify your Administrator. "

Can you tell anything from this to help me fix this? Since I haven't used this feature, I don't know what to tell him to do.

Thanks
Paul