Upcoming Changes to Exchange Property Limits: Everything You Need to Know

Microsoft has announced significant changes to the allowed size and count of values for various Exchange properties. These alterations will be implemented in two phases between late September 2024 and late November 2024. Here’s a detailed breakdown of these changes and their implications for your organization.

Summary of Exchange Property Limits Update

Microsoft is implementing changes to the allowed size and count of values for various Exchange properties. These changes are set to occur in two phases: between late September 2024 and late November 2024. Below are the details of these changes and how they might affect your organization.

Phase 1: Starting in Late September 2024

Affected Properties and New Limits

Property Max Length (characters) Max Count (entities)
CloudMSExchUCVoiceMailSettings 1123 20
MSExchArchiveName 512 20
MSExchResourceMetadata 1024 20
MSExchSenderHintTranslations 500 20
ExchangeResources 1024 20

Phase 2: Starting in Late November 2024

Affected Properties and New Limits

Property Max Length (characters) Max Count (entities)
CloudMSRtcPolicyAssignments 128 45
MSExchResourceSearchProperties 1024 35
CloudMSExchUserHoldPolicies 40 1150
MSExchExtensionCustomAttribute1 2048 750
MSExchExtensionCustomAttribute2 2048 750
MSExchExtensionCustomAttribute3 2048 400
MSExchExtensionCustomAttribute4 2048 400
MSExchExtensionCustomAttribute5 2048 250
ValidationError 948000 10
ProxyAddresses 1123 1200

Clarification on ProxyAddresses Limits

Microsoft clarified the limits for the attribute proxyAddresses to a fellow Reddit user. This attribute will likely be the main pain point for most organizations. Here’s Microsoft’s response:

“The advisory MC884017 specifies that the proxyAddresses attribute has a maximum length of 1123 characters and a maximum count of 1200 entries. Here’s the clarification:

  • Maximum Length of 1123 Characters: This refers to the total length of all the addresses combined in the proxyAddresses attribute. It means that the sum of the lengths of all the email addresses and aliases cannot exceed 1123 characters.
  • Maximum Count of 1200 Entries: This means you can have up to 1200 unique addresses (aliases) in the proxyAddresses attribute.

So, you can have up to 1200 unique addresses, but the combined length of all these addresses must not exceed 1123 characters.”- Source

Impact on Your Organization

  • Exceeded Limits: If any of these properties exceed the new limits, you will not be able to add new values or update existing values beyond the specified constraints.
  • Policy Enforcement: These limits will be enforced beginning in the specified timeframes for each phase.

Conclusion

By being proactive about these changes, you can ensure that your organization remains compliant and avoids any disruptions to your Exchange services. Review your current configurations, plan necessary adjustments, and update your internal processes to comply with these new limits. Keep your team informed and prepared for these upcoming changes.

You can view more details and stay updated on these changes by visiting the Microsoft 365 admin center.

Source: Microsoft Admin Center

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