Email From?

[Xshare]

I'm using sendmail on OSC, and when an email goes out to a customer, it says it's from [company]@[host].com on behalf of support@[company].com. (changed to protect privacy). This is weird as it should be sending straight from support@[company].com , or at least, I'd like it to. The weirdest part is that it DOES send straight from support@[company].com when it sends out a copy of the comfirmation email to us(the owners of the site), or when it notifies us of something, only when it sends to a customer does it send using the host's email. Are there two different scripts where osC emails the admins, and the customers? How can I fix this? Any help would be greatly appreciated.