Yeah, in general it is not acceptable. The clients who will require this are not the clients you want. Basically, it is impossible to ensure you're not leaking

Yeah, in general it is not acceptable. The clients who will require this are not the clients you want. Basically, it is impossible to ensure you're not leaking information while you have such software installed. There are too many vectors. Unless you literally setup a VM per client and ensure you do not check email on that VM, which I suppose is possible ...