Can't mail externally

[Anon]

Hi!

We have an intranetserver which runs our intranet and then we got another server (SBS/Exchangeserver) which handles all mail.

I have set the smtp in php.ini to point to SBS and made a page that generates mail, it works when sending mail locally but it doesn't work to mail someone outside our network.

(We also have a proxyserver)

Any ideas??

PS. It works fine to mail with outlook...