Recover unavailable account

I have an IMAP account set up in Mulberry that is no longer available. Mulberry has the bad habit that, after a failed connection, forget about all mailboxes in an account until the next successful login. Obviously it is not possible in my case since the mail server is no longer available.

All mail was downloaded in Mulberry for offline use before this happened but consequently I can no longer access the mailboxes in Mulberry. Any suggestions about how to fool Mulberry into reload the mailbox list from disk rather than from the network?

Before this happened, sometimes when I was a on an unstable connection (= mobile internet) and the mailbox list was lost due to a unexpected disconnection I had a trick to make Mulberry reload the mailboxes from disk, something like 'go offline deselecting all mailboxes in the sync dialog' or something similar. Unfortunately I can't recall how I did (or it does not work). Any input would be very appreciated.

Thanks