[MlMt] Re-fetch mailbox list?

[Randall Gellens]

I'm using Mailmate version 1.13.2 (5673) on High Sierra 10.13.6.  I 
tried to organize some messages by creating a new IMAP mailbox and 
moving messages from a virtual mailbox into it, but Mailmate kept 
reporting IMAP errors.  So I quit Mailmate and used Telnet to manually 
create two mailboxes under a new mailbox and copy the messages it them.  
No matter what I try, I can't get Mailmate to see these new mailboxes.

--Randall