So use a secure messenger that isn't tied to your phone. Wire is an example. I'd strongly prefer Signal, because the reason Signal is tied to your phone is so they can piggyback on your contacts database and not keep a plaintext contact graph serverside where it's vulnerable to interdiction. But Wire is still vastly better than encrypted email.
using the contacts feature of the phone, in most cases means the contact graph is shared/synced with google, apple servers. It's great Signal does not need a copy, but by outsourcing the contacts they have already leaked and its just pretending to solve the problem.
