I have tried and tried to get out to the internet after my Xp machine successfully connects to my rooted Htc evo 4g droid as a wireless network hotspot, using AndriodTether. IThe xp computer shws that it has sucessfully connected but then the computer starts and then stops the internet connection after a minute or so. Then I built another xp computer thinking they had some software stopping the connection in the old one. I cant even get out with flesh install of Xp so I went and got PDAnet software and I can use usb wire thether OK...but no email unless I pay. So I am still interested in why I cant get out via the wireless tethering while my MAC-head roomate can all day on the same confergeration.
free tethering is against the rules. do so at your own risk.
since you obviously aren't paying for the "tether option" on your wireless plan it all comes down to how the system perceives your data usage. if the software connects like it would via the official (normal) way then the data is perceived as coming from an external source and is shut down by the wireless provider since you do not have the "tether option" on your plan. the best free tether apps make the data seem like it is originating from your phone to get around that.
i've heard that pdanet works but that it has fits and may require a few stop/restarts to work. i've also heard that it quits working intermittantly. i've also heard like you've stated that email might not work.
in general, wireless companies are causing all the problems. why should it matter if you use 2gb of data on your phone or 2g of data via a laptop tethered to your phone? it doesnt.... but wireless companies are very greedy as we all know. the reasons wireless companies give to defend such practices can only be described as pathetic. the legal issues regarding tethering are what is stopping full access by most (notice i said most) apps and options out there.
you said you were rooted...
you might want to look into the miui rom if it is available on your device. dont worry about it not having an app drawer, you can run another launcher instead to give you one. it includes a wireless hotspot feature which doesnt seem to be limited. you can play games, view secure websites, do email (at least webmail i know) as well as everything else as far as i know since the data packets appear to the network to be phone-originated.