New inbox

Hi,
as per the [screenshot](https://private-user-images.githubusercontent.com/35609369/579978768-95bb6520-a891-43dc-abce-509bb607069e.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.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.qVxVx3xeeeTkMo4bgJdyRCsZ4npWf8463cmnW1xJRfw) there should be a button to create an inbox.

My homepage only lets me login. Where/how do we sign up? Thanks

Start by reproducing the homepage and tracing the existing login entry point shown in the issue and screenshot. Identify where a user should create an inbox and how signup fits into that flow; done means the homepage provides the requested create-inbox action and users can reach signup rather than only login.

Written by the indexing model from the issue text.