How do I get emails from ubbthreads to go out with a specific email address. They currently go out to the system administrator, but I'd rather direct them to a specific account. I assume this is handled via php.ini, but not 100% sure.

Yup, I'm fairly certain this is in the php.ini config. Had to change this myself.

So that means if your sharing a system with others, you may not be able to change this?

If it is using Sendmail then it should go out with email address from the config.php I am not sure on SMTP but I think the default is what ever they have in the php setting. a good way to check would be to create a group and have only your own account in the group then send a mass message to only that group and see what the header looks like

It should go out with the email inside your config file. (The "contact us" email address).