Pepper's iMessage
Pepper will be able to send iMessages from its own Apple account, never yours, and only with your OK. For example, it could send daycare photos to a family group.
iMessage sending isn't built yet, so the dashboard's Connections page lists it under Planned. You can prepare the Mac now by making a second macOS user and signing it in to Messages with Pepper's account. See A second user for Pepper's iMessage. The outbox agent, the piece that does the sending, isn't part of Pepper yet.
The plan is to send by iMessage first and fall back to SMS.
Phone line
Pepper can answer calls through a spare Android phone plugged into the Mac. The Android bridge is that phone plus a small call server on the Mac. The phone signs in to the server, and Pepper talks…
Gmail
Not built yet. When it is, Pepper will read your email the way it reads the chats you connect: promises and requests become follow-ups, and Ask, where you ask Pepper questions, can search it. It will…