Firstly - I'm not an SFDC guy... so forgive me if I don't quite get the terms correct...
I'm working on requirements for integration and authentication across multiple systems, with the goal being that "Customers" and "Partners" will have access to our portal, which in turn links through to other systems like ServiceNow, Salesforce, etc. We are looking to do this using their 'email address' as their login ID in all systems.
Here's a scenario: Customer X logins into our portal and wants to request an additional service, clicking that link should either take them to ServiceNow (where no sales transaction is occurring) or potentially SFDC-CPQ (not sure yet if we plan to have customers 'self-generate quotes'). We want all that to happen without multiple login prompts.
Everything seems to be coming together except for SFDC as it seems user IDs need to be 'globally unique'. So I believe that means, if firstname.lastname@example.org is already using SFDC in their own organisation, we can not set them up as a user in our SFDC as email@example.com already exists as an SFDC user.
So the question - is that true for 'community users' too or is it handled differently? Surely many resellers are SFDC users internally, and also access their vendors SFDC systems and they don't have separate user ID / logins for each one??
Don't want to reinvent the wheel... so does anyone have a wheel out there for me look at?