[ale] Sendmail woes

[JANINDRA at MS.NDCORP.COM]

I have a home network setup that consists of 4 PCs.

1 - Linux (running apache, smb, sendmail, the works)
2 - Windows98 
3 - Linux (bare minmum; used for logging)
4 - Linux (firewall/ gateway)

I have no problems moving from machine to machine or sending mail from Linux
to Linux. I can happily cruise the web from any machine too. However when I
try to send mail from Linux to the Internet, my mail gets rejected. I can
send mail from Windows to the Internet with no problems which makes me
suspect my sendmail configuration is the culprit. What should I be looking
for? Does it have something to do with masquarading?

Thanks,
Randy