Where would those changes be made? Where we log in to the domain, and access email settings? I don't have access to that, but can forward that on to the site owner who does.
Having said that, the issue is slightly complicated again, as the address the form needs to use is then being forwarded to another address. (Its overly complicated, I know, but the site owner has his reasons!)
So I don't know if using a Gmail address will be a solution.
Basically, the site is www.oursite.com, and there are forms getting sent to a few people in the related industry.
So the site owner has set up various email addresses for them, eg firstname.lastname@example.org, which then forwards to their actual email address.
It works fine just using their actual address, so its a bit of a pain it needs to be so convoluted!