Problems sending mail

[scadet7]

Need some info. I have an exchange server on my network behind the my wingate firewall. I also have an e-mail address that I always used via my isp using my MS outlook. Prior to installing the wingate I was able to use both my e-mail address from my exchange server along with my isp e-mail address. After installing wingate I'm experiencing problems sending mails. Receiving mails seem to be working fine. On the pc running the wingate/gatekeeper I have port 110 and 25 mapped to point to exchange server's ip address 192.168.1..
On my desktop pc (with widnwos xp) with MS outlook this is my config.
1.The default gateway is the wigate proxy server 192.168.1.10
2.The ISP e-mail account pop3 server is set to my isp server & the smtp is also set to my isp
3.My exchange server e-mail address is set to use my local exchange server's address 192.168.1...

Not sure is my config is correct since sending mails from my network seems to be a problem.
Any suggestions is welcome.

Thanks,
Steve