Can we increase the concurrent sessions allowed to connect to office 365?

Hi @Jaikumar Ghadmode

Thank you for reaching out to the Microsoft Q&A Forum. 

Please understand that our forum is a public platform, and we will modify your question to cover your organization domain name in the description. Please notice to hide these personal or organization information next time you post error or some information to protect personal data. 

It looks like your application encounters throttling issues when multiple JVMs are accessing Office 365 mailboxes through Microsoft Graph. This behavior is typically related to concurrency limits enforced by the Graph API. 

Based on my research using publicly available Microsoft documentation and resources, the issue appears to be related to the MailboxConcurrency limit. This limit allows a maximum of four concurrent requests to a single mailbox at any given time. It seems to be a built-in service limit, likely intended to help maintain stability and consistent performance across Microsoft 365 tenants.. Unfortunately, there doesn’t appear to be a way to increase or customize this limit at the moment. 

One possible way to work around this is to use JSON batching with the dependsOn property. This approach allows you to structure your requests in a way that ensures they’re processed sequentially, which can help avoid hitting the concurrency limit when multiple JVMs are active. 

You might find these articles helpful for further reading: 

• Microsoft Graph service-specific throttling limits 
• Combine multiple HTTP requests using JSON batching 

I hope this helps. If you have any other questions, feel free to reach out again.

If the answer is partially helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".    

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.