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Summary: Are you getting throttling errors while accessing Exchange Web Services (EWS)? To resolve it, you must increase EWS throttling policy in Exchange Online. You can do it using the Office 365 Admin Center. To avoid such errors, we recommend using a professional Exchange migration tool that allows controlled migration.
To handle the needs of millions of users accessing Exchange Server, several throttling policies are integrated. You must have felt it. Sometimes, the performance is high while other times it’s low. This is done to implement the fair usage policy and make sure no user ends up consuming most of the resources. In Exchange Online, EWS throttling policy helps to manage the server resources.
For an Exchange admin or a working professional who constantly has to deal with Exchange Online, it’s crucial to know what EWS throttling is and how to manage it. Read this complete blog to learn more about it. This is a must have skill to maintain server performance during tasks like tenant-to-tenant migration or heavy database synchronization.
What is EWS Throttling in Exchange Online?
You can think of the EWS throttling in Exchange Online as a mechanism to prevent overuse of resources. Microsoft developed it to make sure resources are available for every user who is accessing the Exchange Online.
In Exchange, every user account is given a specific usage limit that defines how many operations users can perform. This is implemented with a special algorithm called Token Bucket. When the service you are currently using crosses these limits, Exchange Online will interrupt you.
In such a situation, errors like “503 Service Unavailable” or “ServerBusyException” are seen. Sometimes, Exchange Online may even ask you to retry the operation after a period of time. A few of the parameters Exchange uses are CutoffBalance, EWSMaxBurst, EWSMaxConcurrency, EWSRechargeRate, etc.
Top Reasons to Increase or Disable EWS Throttling
EWS Exchange Online policy modification can happen due to different factors, such as:
- Smooth Backup Process: Backing up thousands of mailboxes can hit the EWS limit and slow down the process. For fast mailbox copying, admins modify the policy.
- Data Migration: It is the most common trigger. When you move terabytes of mail data during an Office 365 migration, you require high server resources. EWS throttling in Exchange Online will interfere with it. Increasing the EWS throttling will help with faster data migration.
- Application Performance: If you are experiencing issues while using an Exchange Online application like eDiscovery, you should increase EWS Exchange Online policy.
- Application Testing: Microsoft developers when needed to deploy and test custom applications, often manipulate EWS throttling policy.
- Specific Application Use Case: In case an app is utilizing resources heavily, developers have to change the policy for that application to prevent resource overuse.
Increase or Disable EWS Throttling using Office 365 Admin Center
Unlike the Exchange On-Premises Server, which uses cmdlets to modify throttling policy, the cloud environment (Exchange Online) relies on Admin Center. Increase EWS throttling in Exchange Online with the following steps:
Step 1: Login to your Office 365 account using the admin credentials and navigate to Admin Center.
Step 2: In the left pane navigation window, click Show All.
Step 3: Click and expand the Support button, then select the New service request option.
Step 4: In the search field, search for “throttling”. Then, select the “Increase EWS Throttling Policy” option and press Enter.
Step 5: Click the Run Tests option to run the diagnostic tests for throttling.
Step 6: Use the Days dropdown and select (30, 60, or 90) for how many days you want to disable EWS throttling in Office 365.
Step 7: Click Update Settings to save the changes and increase EWS throttling policy.
Avoid EWS Throttling with these tricks
Follow these tricks to avoid interruption or lag due to the EWS throttling policy. These are most beneficial when you need to migrate multiple mailboxes.
Filter Unnecessary Data
Move only what’s needed and discard any obsolete or irrelevant data. Be it emails, attachments, contacts, calendar entries, or shared data, filter out every single item from the source before you begin a task like tenant-to-tenant Office 365 migration.
Run the Task During Off-Peak Hours
Millions of users use Exchange Online resources every second. To minimize the load on the server, you should choose a time slot when the server is least busy. This will help to speed up the resource-heavy task while minimizing server downtime.
If migration is your top priority and you cannot wait till weekends, categorize the high-priority emails to migrate them first. Start with small size emails first and move the heavy data items (emails with attachments > 25MB) on weekends or overnight.
Choose the Right Migration Strategy
Based on the number of users and data volume, choose the best migration strategy for your case. You can choose from:
Cutover Migration: Best when you have less than 200 mailboxes. Migrate all of them at once in a single event. It’s simple, fast, and suitable for small organizations.
Staged Migration: This approach reduces risk and downtime. Here, you create batches of migration and run them over a period
Pre-Staged Migration: Move old data first and then move the recent data in one final go. This method is highly efficient for large enterprise-level migration.
How Exchange Admins Bypass EWS Throttling Policy Restrictions
Exchange admins and IT professionals, performing mailbox migration or backup, use a dedicated Exchange migration tool. Our Kernel Migrator for Exchange tool allows users to migrate mailboxes across forest and domains. Furthermore, you can also move Public folders or Exchange Groups with original folder hierarchy. The tool is designed and developed by engineers skilled in Exchange architecture. Powered with simple UI and robust algorithms, it’s a must-have tool for every admin.
A few of its key functionalities are:
- Migrate data between Exchange On-Premises, Hosted Exchange, and Exchange Online
- Pre-migration analysis of the source mailbox to help with an error-free Exchange migration.
- Mailbox mapping for precise data transfer with complete data integrity
- Allows rolling back failed migration and reverting the destination server to an earlier working version.
- User-friendly interface to setup and run multiple migration jobs in just a few clicks.
- Offers data filters and scheduling features to minimize downtime.
- Uses Agents (connected systems) for load sharing during large-scale mailbox migration.
Conclusion
To handle heavy operation, you need to manage EWS throttling. You can increase the EWS throttling in Exchange Online temporarily using Office 365’s admin center but cannot disable it. However, the EWS throttling policy is implemented to protect the integrity of cloud resources. Be careful when you make changes to them. To avoid getting throttling errors, filter data, schedule migration, and run the migration in batches. Alternatively, you can use the Kernel Migrator for Exchange tool that can do it all automatically.
Frequently Asked Questions
The EWS throttling policy cannot be permanently disabled for specific accounts. You can only increase EWS throttling in Exchange Online for a maximum period of 90 days.
No, Exchange Online does not support the throttling policy cmdlets like the On-Premises Exchange Server does. To increase EWS throttling in Exchange Online, you have to create a new service request in Office 365.
Generally, no. But since all Microsoft 365 services (EWS, SharePoint, Teams, etc.) share underlying tenant resources (CPU, RAM, storage, etc.), heavy resource utilization by EWS may affect other Microsoft apps.
