[Evolution] Evo subfolder corrupted after upgrade

["Johnson, Daniel" <johnsondanl uwstout edu>]

Last evening my son the Linux geek performed his triennial upgrade of the system at my office ("why upgrade 
if it's working?") and Evo was upgraded from some pre-SQLlite version to 2.30.1.1

Only 2 issues seem to have emerged, one of which is this:
I have Inbox subfolders, one of which is for emails from within the healthcare system for which I work.

The old version of Evo had been running when the upgrade was begun, and was terminated by a remote reboot.
After upgrade,
 - I launched Evo; there was a flurry of folders-activity messages, and then I was looking at the usual UI, 
with one clear difference: the number of unread messages in each folder did not display.
 - I read 2 messages in my Inbox/Mayo-System subfolder, and was pleased to notice that the current Evo 
version translates winmail.dat attachments to the enclosed file. Yay!
 - I then marked one message in this folder for deletion.
It then occurred to me that Evo might need to do some further cleanup, so I Quit Evo and relaunched.
 - Now the number of unread messages displayed (but not the same # as displayed by the prior version) BUT, 
with each message in my "work" Inbox subfolder, I see this error message (the message # differs, of course)
 -  Unable to retrieve message
Cannot get message: 9489 from folder /home/danlj/.evolution/mail/local/Inbox.sbd/Mayo-System The folder 
appears to be irrecoverably corrupted.

How ironic that the ONLY important subfolder in my mail is the one corrupted.

It's sort of important to be able to recover the contents of this folder. 

Any hints on how to proceed?

Thanks
Dan Johnson
reply to: johnson danl mayo edu