The above solution should have worked, but i found a different solution that require no changes to the powergallery files and it should be much easier to implement.
Please remove the changes that i suggested to the power gallery files. and replace the products_detail.php and products_detail_lookup.php file with attached files that i have sent. Make sure to create a backup of your current files.
I'm not sure where the forum notifications will come from, but i would assume it should be a webassist domain. Can't you mark the emails as not spam in your spam filter so they come directly to your Inbox the next time.