Bandwidth limitations when moving mailboxes in Exchange 2019

Hi @User9183

Thank you for posting your question in Microsoft Q&A. 

Please note that this is the Russian forum. We kindly recommend posting your question in Russian so that more community members can assist you. Alternatively, if you prefer to continue in English, you may also consider posting on the English forum. We sincerely appreciate your understanding. 

We understand that you're considering limiting bandwidth during mailbox migrations from the cloud to on-premises. Based on my research, Microsoft does not currently provide an official method to directly throttle bandwidth for mailbox moves using the New-MoveRequest cmdlet or by configuring the MSExchangeMailboxReplication.exe.config file in Exchange Server.

However, there are a few potential workarounds you might consider:

Use Smaller Batches: 

Instead of moving many mailboxes at once, break them into smaller batches and stagger the move requests. 

Use Network-Level QoS 

If you prefer to manage this at the network level, or if the throttling policy isn't granular enough, you can work with your network engineers to implement a Quality of Service (QoS) policy. 

This involves configuring your firewall or router to identify and rate-limit the specific traffic from the migration. 

Traffic Source: The traffic will originate from Microsoft 365's IP address ranges. You can find the official list of URLs and IP address ranges online. 

Traffic Destination: The destination will be the external IP address of your Exchange 2019 server's Client Access Service, specifically the MRSProxy endpoint. 

Port: The traffic will be HTTPS, so the destination port will be TCP 443. 

Your network team can create a rule, for example: "Any traffic from Microsoft 365 IPs to our Exchange server on port 443 should be limited to X Mbps." This is a very effective but less flexible approach, as it requires changes on network appliances. 

This summary is based on my findings from the community and several relevant threads. However, it may not fully address your specific goal. To get more targeted support, I recommend posting a thread on the Microsoft Tech Community forum. It’s a great platform for deeper technical discussions and connecting with individuals who have hands-on experience and expertise. They’re best positioned to provide guidance and valuable insights on this topic.    

Apologies for redirecting you to the related development team support as the moderators in this community have limited resources to check the backend information, and to get the fast and better assistance we requested for it.   

If you have any additional concerns, feel free to comment below. I would be more than happy to assist. 

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