When you create an account you provide an account secret and password that are never shared, but are used to generate a cryptographic key used to access your data.
Safe does not include any form of public identity, and email is not even part of core network (just data storage).
It is up to application developers to publish apps that will provide things like messaging etc, and (potentially) up to each app separately to define any sort of public address for you to exchange data with other users.
Personally, this concerns me quite a bit, as I have always felt one of the biggest architectural flaws in the original Internet was a lack of identity management.
I am hoping that early developers have the foresight to collaborate on how to define and shared identity schemas/personas so we don’t end up with the mess of having separate identities for every app (unless as a user you choose that), but since the Safe demo apps all create separate identities a lot of devs will follow that example.
In all honesty, they probably won’t, and this will end up being a huge missed opportunity for Safe