In Settings > Channels > Email, you can manage email related settings.
You can create senders (display name, sender address) that users are able to select when creating orchestrations.
Batch also offers APIs to facilitate opted-in profiles imports.
See this technical documentations about the first technical steps to send emails with Batch and manage properly email imports from your former emailing solutions:
See also this article helps setting up Apple Privacy Relay:
Note that beyond giving access to a rich set of data manipulation capabilities, Batch provides Enterprise grade support for deployment and onboarding.