nnimap unable to open server unknown service 993

["Steinar Bang" <sb@dod.no>]

Platform: Windows 7,
           emacs 24.3.1,
           Ma Gnus v0.8 (git HEAD),
           GNU TLS gnutls-3.0.9-w32-bin.zip from  
http://sourceforge.net/projects/ezwinports/files/

Summary: I haven't found a solution for the problem yet.  Any  
assistance/ideas/guesses will be appreciated.

What follows are my experiments and results.

When connecting I get the following messages in the minibuffer:
  Opening nnimap server on privat...
  Opening connection to imap.mydomain.com via tls...
  Unable to open server nnimap+privat due to: Unknown service: 993
  Opening nnimap server on privat...failed:

Connecting to the same IMAP server with Opera on the same computer,  
succeeds (so there should be no firewall issues).

The nnimap server is defined as a secondary select method:
  (setq gnus-secondary-select-methods
        '((nnimap "privat"
   	        (nnimap-address "imap.mydomain.com")
                 (nnimap-authenticator cram-md5)
                 (nnimap-stream ssl))
          (nntp "news.gmane.org")
          (nndiary "")
          ))

I have installed GNU TLS by downloading the bin.zip file from the above  
URL, extracting all DLL files in the bin directory of the zip file, and  
dropping them into the emacs bin directory.  That makes emacs 24 pick them  
up and use the built-in TLS.

I have googled for this error message and found this thread:
  https://groups.google.com/forum/?fromgroups=#!topic/gnu.emacs.gnus/vTPHwp0hVak
which probably isn't the issue, because
  1. My c:/Windows/System32/drivers/etc/services contain the line:
      imaps             993/tcp                           #IMAP4 protocol  
over TLS/SSL
  2. I'm running git gnus HEAD, which should contain the fix that Lars  
talked about at the end of the thread

I found this thread which looked more promising:  
http://thread.gmane.org/gmane.emacs.gnus.user/14695

 From that thread it looked like the cause of the error message, might be a  
certificate issue. My IMAP server's certificate is signed by  
http://cacert.org so not having the Cacert.org CA certificate installed  
where GNU TLS could find it, looked like a likely culprit.

The question was then: where should I drop the cacert.org CA certificate  
so that the GNU TLS DLL in emacs would pick it up?

Googling some more, I found this:
  http://www.gnu.org/software/emacs/manual/html_node/emacs-gnutls/Help-For-Users.html

The value of gnutls-trustfiles, was:
  ("/etc/ssl/certs/ca-certificates.crt" "/etc/pki/tls/certs/ca-bundle.crt"  
"/etc/ssl/ca-bundle.pem" "/usr/ssl/certs/ca-bundle.crt")

I downloaded the cacert.org class 1 sertificate from  
http://www.cacert.org/index.php?id=3

I saved the downloaded file as  
C:\ProgramFiles\emacs-24.3\etc\gnutls\cacert.org_root.crt

I evaluated the following in the scratch buffer:
  (push "C:/ProgramFiles/emacs-24.3/etc/gnutls/cacert.org_root.crt"  
gnutls-trustfiles)

I then tried to start gnus, but I got the same issue.

I have tried the log levels 1, 2 and 5, by evaluating
  (setq gnutls-log-level 1)
and then tried `M-x gnus', and when that didn't give anything meaningful,  
I evaluated
  (setq gnutls-log-level 2)
and then tried `M-x gnus', and when that didn't give anything meaningful,  
I evaluated
  (setq gnutls-log-level 5)
and then tried `M-x gnus'.

But not even log level 5 gave me any clue that there were CA issues with  
the nnimap connection.

It did show that GNU TLS was active, though.  And that GNU TLS used the  
cacert.org cert, when trying to open an nntps connection to news.gmane.org:
  Opening nnimap server on privat...
  Opening connection to imap.mydomain.com via tls...
  Unable to open server nnimap+privat due to: Unknown service: 993
  Opening nnimap server on privat...failed:
  Opening nntp server on news.gmane.org...
  gnutls.c: [1] (Emacs) allocating credentials
  gnutls.c: [2] (Emacs) allocating x509 credentials
  gnutls.c: [2] (Emacs) using default verification flags
  gnutls.c: [1] (Emacs) setting the trustfile:   
C:/ProgramFiles/emacs-24.3/etc/gnutls/cacert.org_root.crt
  gnutls.c: [1] (Emacs) gnutls callbacks
  gnutls.c: [1] (Emacs) gnutls_init
  ...[snip! news.gmane.org stuff]