For engagement levels, a tag usually works best so you can easily add/remove conflicting information. 2. Update domain dns be industry leads aware of your current dns settings and the records (if any) that will need to be updated when changing platforms. For example: do you have a dmarc policy in place for your domain?
Do you industry leads currently authenticate your emails with your own dkim? Maintaining the same authentication approach is key to a smooth transition with your domain reputation. The goal is to change as little as possible when you are already going to send emails through a new ip address.
If you need help with this setup, we industry leads can help. Remember to document all domains and subdomains you are actively sending from. You'll want to use these same domains when you start sending to your new platform. This transfers the reputation of your existing domain to your new email platform.