Send 4 reqeusts at the same time, but still get "Application is over its MailboxConcurrency limit."

Question

Hi,

I am developing an application that can create and delete appointments in a calendar. I have read through the Graph throttling-limits documentation and understand that only 4 concurrent requests can be sent. Therefore, I created 4 threads to send out the requests. However, I am still receiving a 'TooManyRequests' error. I am also using JSON batching to reduce my requests, but it hasn't helped.

Finally, I found someone who said, 'Outlook resources, such as mail and calendar, can only handle four requests targeting the same mailbox.' If this is true, how long should I wait before sending another request to the same mailbox?

Thanks.