You probably need plain-text access so that messages can live on the server rather than the device. It is a common desire for users to (1) use more than one de

You probably need plain-text access so that messages can live on the server rather than the device. It is a common desire for users to (1) use more than one device; (2) sign in a new device and have access to message history; (3) message search to work. You can probably put these together in an end-to-end encrypted system -- can apple access old messages on a new device? -- but it's very complex.