500 error clicking links in newsletter

None of the links in my automatic newsletter are working.

Clicking on the URL gives an “HTTP 500 Server Error” page. The URL displayed is like:

http://www.rodneylacroix.com/?email_id=25&user_id=86&urlpassed=aHR0cDovL3d3dy5yb2RuZXlsYWNyb2l4LmNvbS9ibG9nLw%3D%3D&controller=stats&action=analyse&wysija-page=1&wysijap=subscriptions

I have been advised by my users that these don’t work. I tried deactivating/reactivating mailpoet but the links in the newsletters still seem broken. HELP is hugely appreciated here.