Specifically, I am finding that although Exchange doesn't appear to support the STARTTLS capability (if you know how to turn this on please let me know!), it does apparently listen to port 993 for connections that begin with a TLS negotiation, followed by IMAP.
SSL negotiation, not TLS negotiation. Specifically, the SSLv23 method, as opposed to the TLSv1 method.
I suspect this is considered pretty non-standard, and out of scope for c-client. Nonetheless, its a problem I need to solve.
It's standard, but an older standard; and it is supported by c-client.
I was hoping for suggestions on how I might go about making this work.
The work is already done for you.
Just add "/ssl" after the host name in the mailbox specification, e.g. {imap.example.com/ssl}INBOX
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.