[Dovecot] imapc Proxy to IMAPS Exchangeserver?

[Ralf Hildebrandt]

I'm trying to adapt http://wiki2.dovecot.org/HowTo/ImapcProxy
to our Exchange Server, which has LOGINDISABLED on Port 143, and I
offering LOGIN on Port 993.

How do I go about this?

Simply changing imapc_port to:
imapc_port = 993
doesnt work:

Connected to localhost.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot (Ubuntu) ready.
. LOGIN hildeb password
. NO [UNAVAILABLE] Temporary authentication failure. [mproxy:2014-05-16 09:33:23]
. LOGOUT
* BYE Logging out
. OK Logout completed.
Connection closed by foreign host.

Logs:

May 16 11:33:04 mproxy dovecot: master: Dovecot v2.2.9 starting up (core dumps disabled)
May 16 11:33:21 mproxy dovecot: auth: Error: imapc(exchange-imap.charite.de:143): Command '2 LOGIN "hildeb" "password"' failed with BAD: 2 Command received in Invalid state.
May 16 11:33:21 mproxy dovecot: auth: Error: imap(hildeb,::1,<bjeUGoH53AAAAAAAAAAAAAAAAAAAAAAB>): Disconnected from server
May 16 11:33:21 mproxy dovecot: auth: Error: imapc(exchange-imap.charite.de:143): Authentication failed: Command received in Invalid state.
May 16 11:33:26 mproxy dovecot: imap-login: Aborted login (auth failed, 1 attempts in 8 secs): user=<hildeb>, method=PLAIN, rip=::1, lip=::1, secured, session=<bjeUGoH53AAAAAAAAAAAAAAAAAAAAAAB>

But why is it still using port 143?

-- 
Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | http://www.charite.de