Limitations of MS Graph Service

The Outlook service enforces these limits for every app ID and mailbox combination, meaning a specific application accessing a specific user or group mailbox:

• 10,000 API requests within a 10-minute period
• Up to four concurrent requests
• A maximum of 150 megabytes (MB) uploads ( through PATCH, POST, or PUT) in a 5-minute period

However, exceeding these limits for one mailbox does not impact the ability of the application to access other mailboxes.