Buster problem?

Yesterday, I updated my Debian Stretch system to Debian Buster.  Everything went 
smoothly. Kmail 5.9.3 seems to still work just fine.

This afternoon I received an email, purportedly from the Washington Post, which I 
could not open.  My filters had put in the the Spam Probable folder.  When I tried to 
open it I got this error: "please wait while the message is transferred," though 
waiting doesn't help.

When I try to move this message to my inbox, kmail says: 

"Unable to retrieve item from resource: [LRCONFLICT] Resource 
akonadi_maildir_resource_0 tries to modify item 231290 () (in collection 125) with 
dirty payload, aborting STORE."

I thought the problem might be corrected with the anti-spam filter, but I can no 
longer find the anti-spam wizard.

Any suggestions?  So far just ignoring it seems to not hurt anything.

John White