IMO, it only becomes unnecessary to be as safe as possible when it stops you from being able to communicate.

You can use encrypted email (such as protonmail) to communicate although keeping communication encrypted is only easy if the Domme also has a protonmail account (otherwise you have to jump thru some hoops).

From a texting perspective, Signal is the best option for encrypted communication but WhatsApp also works but the Domme must also have that app.

Chances are if you are going to have a problem, it is not because of intercepted communication. It is most likely you being sloppy or your device being compromised and it being tied back to your legal ID.