If you search your PM inbox and have more than one page of results clicking on subsequent page numbers or the "next" link does not carry the query params over to those pages.
Example first page URL:
https://pinside.com/pinball/connect/pinsidemail?pinsider_id=&pinsider=&query=test&ft=1
Second page click gives this:
https://pinside.com/pinball/connect/pinsidemail/page/2
It should give this:
https://pinside.com/pinball/connect/pinsidemail/page/2/?pinsider_id=&pinsider=&query=test&ft=1