Apache as proxy in intranet + Outlook express

[kio]

I have created a small intranet using Apache 1.3.24
I added with success PHP + CGI + and VirtualHosts, etc. To share the access to Internet I loaded the Proxy service that has Apache.
Everything works correctly. The IE 6 in the clients browse without problems, but I have difficulties (in fact I am not sure if it is possible to make it) to allow that Outlook Express can use the proxy of Apache to send and to receive mail.
My current Apache proxy Directive look this:

<IfModule mod_proxy.c>
ProxyRequests On
<Directory proxy:*>
Order deny,allow
Deny from all
Allow from mak2 mak3
</Directory>
ProxyVia On
CacheRoot &quot;x:/Apache/proxy&quot;
CacheSize 5
CacheGcInterval 4
CacheMaxExpire 24
CacheLastModifiedFactor 0.1
CacheDefaultExpire 1
NoCache
</IfModule>

In IE6 (in the clients - mak1 -mak3) Internet Options-Conexion-Lan roxy settings--> 192.168.0.5 port 80 for all protocols (192.168.0.5 is IP Machine where Apache are running)
In Outlook i setting defaults smtp and pop 3 for my ISP provider
Somebody has solution for this ?