Nylas creates only one grant per email address in each application.
If a user authenticates with your Nylas application using the email address associated with an existing grant, Nylas re-authenticates the grant instead of creating a new one.
So in your scenario where different users connect the same email (Gmail/Outlook), there will be a single grant ID for that email address within your Nylas application, not multiple grant IDs.
Let us know if you have any other questions.
Many thanks,
–Pracheta Munje
Support Engineer, Nylas