Route all traffic to a particular domain/subdomain without VPN I'm using OpenVPN through Viscosity.

Is it possible to set it up in such a way that all traffic would go through the VPN, except traffic to a domain I'd specify (and all its subdomains, etc.)?

So only that one domain I'd specify would not use the VPN.
You'll want to add a static route to addresses you want, specifying the first hop in the chain, which can be an IP address or network device.

Here is a related question that involves establishing the static route at boot time.

Setting a static route every boot with launchd / plist is failing