Hi Elias,
Unfortunately there is no easy way to delete accessions from the Appraisal Module once imported. If you want a version of the email collection omitting those messages, I think you would have to start over with a new collection and skip importing those files that you don't want to include.
Sorry that there isn't an easier way to handle this issue - please let me know if you run into any other problems going forward.
Best,
Sally DeBauche
Digital Archivist
Stanford University Libraries
Stanford, CA 94305-6010