Issue Summary

First Occurrence — August 7 - August 21, 2023

Some customers using Veeam Backup for Microsoft 365 to back up Microsoft 365 Exchange data may have experienced an unexpected increase in the volume of data being backed up between August 7 and August 21, 2023. Microsoft confirmed at that time that this was due to a limited incident, which caused older emails to unexpectedly resurface in some Microsoft Exchange Online environments, resulting in increased email data in some Exchange Online mailboxes.

Second Occurrence — March 8 - April 23, 2024

Beginning on March 8th, 2024, Veeam Support started to receive reports from customers about an unexpected increase in the amount of Exchange data being backed up. Based on the experience with the first occurrence of this issue, Veeam's development team promptly engaged with Microsoft Support to begin investigating the root cause.
 

Backup Impact

Emails that were changed, causing them to resurface unexpectedly, must be captured by Veeam Backup for Microsoft 365 to ensure backup continuity. Even though these emails may have been previously backed up, their modified state means they must be backed up again. There is no way to reclaim the space utilized by the backup of these resurfaced emails, as it is technically changed data.

This situation is discussed in further detail in Veeam's RND forums.
 

Statement from Microsoft

^{Updated: 2024-04-23}
Microsoft has provided Veeam with the following statement to share with our mutual customers:

Due to changes we [Microsoft] are making to optimize search and compatibility functionality within our service, this action led to re-indexing for some of our customers' data. The re-indexing is not indicative of a change to fields material to our BCDR and storage partners, so we will be working on a change to minimize the re-indexing that is prompting another backup of customer data. We made changes over the weekend that should pause the unexpected behavior and those changes will be in place until Microsoft and our partners are able to make longer term enhancements to avoid future issues from taking place. Thank you for your patience.

Advised Actions

• Check the reports and monitoring activity from after August 7th, 2023, and March 8th, 2024, to determine if your setup is affected by this issue.
• Any impacted Veeam Backup for Microsoft 365 jobs must be allowed to be completed.
• If you have opened a Microsoft Support Case on behalf of your contract and would like more Veeam details regarding the issue to help address it with Microsoft, or should you have any questions, please don’t hesitate to contact Veeam Customer Support.