Squirrelmail Error

I came across an obscure error using Squirrelmail recently. The
error was just the text "ERROR : Connection dropped by imap server"
after attempting to login with a newly-created user - less than
helpful, and the server logs were no help (I'm using the Dovecot
IMAP server). I was thrown off by the fact that I had recently
migrated this client's installation to a new server, and thought
everything should have worked as it had before. The key turned out
to be that this was a brand-new user account, and that user's
Maildir folders were missing. The easy fix is to create the maildir
folders:

su - newuser 
maildirmake $HOME/Maildir

One odd result of the failure to create the Maildir folders was that
incoming mail was stuffed into an mbox-formatted mailbox named
'Maildir' in that user's home directory. I was able to convert this
to maildir format using a nifty utility called mb2md. Here is the
entire sequence of commands:

su - newuser
mv Maildir mboxfile
maildirmake $HOME/Maildir
./mb2md-3.20.pl -s mboxfile

I then copied an empty Maildir folder hierarchy to /etc/skel so it
would be copied into new user accounts.