From Mike at work:
Looks like Cyrus mail boxes have been case sensitive for some time:
From: http://asg.web.cmu.edu/cyrus/download/imapd/changes.html
Changes to the Cyrus IMAP Server Since Version 1.3
- Implemented the "reconstruct -m" command, for reconstructing the mailboxes file. IMPORTANT: it is necessary to run the command "reconstruct -m" as the cyrus user after upgrading the Cyrus IMAP software from version 1.3 or earlier. We recommend you make a backup copy of the mailboxes file in the configuration directory before performing the conversion.
- Mailbox names are now case sensitive, not case insensitive. "INBOX" is the exception, and is treated as being case-insensitive.
Here is what I found the fix to be. I added the following line to imapd.conf:
lmtp_downcase_rcpt: yes
