[Exim] Smart host and condition - port 25 firewalled

    I am running Exim-4.14-1 under Cygwin (Pierre Humblet port) on my Windows
2000 laptop.  I installed Exim, so I did not have to change mail servers
whenever I moved places.  This procedure has worked extremely well, until
yesterday afternoon when the system administrator at work decided to
firewall port 25:
$ telnet mx2.hotmail.com 25
Results in Connection timed out.  While from our Linux server, telnet to
hotmail does work.

    Now I am trying to configure Exim in such a way, that it passes the message
to the server (smart host?
http://www.exim.org/exim-html-4.10/doc/html/spec.html )  However, whenever
my laptop is connected to the net in another place than work, I would like
to use Exim as it was.  Would it be possible to choose the most suitable,
using for instance 'condition' (chapter 14) in which based on the local host
name it selects the best method?  Could someone help me with the correct
procedures and syntax to resolve my problem?

    If there are other work arounds or better methods, please let me know.
            Many thanks and best wishes,
                Gert