Client want to create a new domain and do SPF/DKIM on that. Is that OK?
yes we can add new domain for that customer and do their dkim/spf. The users email addresses that need to use distro must be under the new domain, you can have mixed domains it's not a problem. The campaign "from email" selection should be restricted to the domain that has been DKIMed that's all. You have to verify the new domain email in order to send distros.