Force STARTTLS connection with IMAP

[Joel J. Adamson]

Hello Fellow Gnusers,

I have the following .gnus.el on two machines running Emacs from bzr[1]
on Fedora 13, connecting to a university IMAP server (Cyrus IMAP):

(setq gnus-select-method '(nntp "news.gwene.org"))
(setq imap-default-user "adamsonj")
;; gnus customization file
(setq gnus-secondary-select-methods
      '((nnimap "UNC"
                (nnimap-address "imap.unc.edu")
                (nnimap-server-port 143))))

(setq gnus-message-archive-method (car gnus-secondary-select-methods))
(setq gnus-message-archive-group "nnimap+UNC:INBOX.Sent")
(setq gnus-gcc-mark-as-read t)

Note that I have not specified `nnimap-stream'.  On my campus
workstation I see a slew of messages as Gnus tries to connect, which
settles on "Connecting with STARTTLS..." and everything proceeds
according to plan (i.e. Gnus connects, downloads messages, etc).  On my
home machine (off-campus), however I get

Opening nnimap server on UNC...
Opening TLS connection to `imap.unc.edu'...
Opening TLS connection with `gnutls-cli -p 143 imap.unc.edu'...failed
Opening TLS connection with `gnutls-cli -p 143 imap.unc.edu --protocols 
ssl3'...failed
Opening TLS connection with `openssl s_client -connect imap.unc.edu:143 
-no_ssl2 -ign_eof'...done

and then nothing happens (Emacs just sits there with no blinking
cursor).

My question is why doesn't the machine at home go through the same set
of protocols, and why does it arrive at a different solution?  Is there
a way to force it to use STARTTLS?  I tried specifying

(nnimap-stream starttls)

and it does exactly the same thing as when I leave it unspecified.

Evolution connects flawlessly from home.

Thanks for any help,

Joel

Footnotes: 
[1]  GNU Emacs 24.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2010-09-25 

-- 
Joel J. Adamson -- http://www.unc.edu/~adamsonj
University of North Carolina at Chapel Hill
CB #3280, Coker Hall
Chapel Hill, NC 27599-3280

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