The "Mark as Spam" command doesn't work

Mailsmith
Just installed v. 3
When I try to mark an email as spam I get this message:
File cache error (read attempted beyond hard limit). Please contact support@mailsmith.org for assistance (application error code: 20615)

I also get many emails showing up as errors with the message:
An error occurred while storing mail.
File cache error (read attempted beyond hard limit). Please contact support@mailsmith.org for assistance (Application error code 20615).

These sound like errors related to Mailsmith’s data store. I recommend contacting Mailsmith support.