[78savette]

This may be a toughie, I have an Iphone 3GS and a couple of weeks ago I added tethering to my ATT plan to serve as my internet service. Actually works great, very inexpensive (added $15 a mth I believe for 5GB), BUT....it doesn't allow me to access my company's email exchange.
Our exchange address is mail.mycompany.com/exchange, have always accessed it from my LT (and other computers) anywhere, clients offices, libraries, friend’s houses, friend's tethered phone (not ATT), using anybody else’s wifi and never had a problem, and still don't, except when I use the Iphone to tether on my LT, it gives me "Error: Access is Denied". Have no problems with any other website, and, not only are my company emails set up on my phone and have been with no issues, I can get on the internet from my phone and it pulls up the exchange no problem, it is just when I use it to tether and try to access the exchange from my LT.
Been talking to ATT numerous hrs the last few days, testing, checking settings, ect. Our Co. IT guy stated from the get go there is no security set up on the exchange server to keep us from accessing it from a hotspot (HS) (even though there is to prevent us connecting to our VPN through a HS), and I guess it's proven because I can access it through other HSs (if I understand HS correctly and there is no difference in tethering a HS (mobile HS?) and a reg HS). ATT doesn't have a clue so they transferred me to Apple CS, who, since I bought the phone 7-10-12 and out of 3 mth warr, wanted $70 before talking to me.
Any advice???? Direction?????

Most likely a phone setting/issue???? Laptop setting/issue???? Exchange security/setting/issue??????