The fkPageID value points to the actual page id which you can search for in EPiServer UI.
The string could be in a page in the Recycle Bin or maybe even in a previous page version…
SELECT * FROM [myEpi6db].[dbo].[tblProperty] where string like '%firstname.lastname@example.org%' or LongString like '%email@example.com%'
This is on a EPiServer 6r2 db.