MailStore mailbox archiving via Microsoft Graph is slower than via EWS
Summary
When archiving mailboxes from Microsoft Exchange Online, archiving via the Microsoft Graph API may take longer than using the Exchange Web Services (EWS) that were previously used. This behavior is expected and results from architectural differences between the two access methods.
Cause
The described behavior does not represent a defect within MailStore.
Microsoft is no longer developing EWS and instead recommends using the Microsoft Graph API to access mailboxes in Exchange Online. The Microsoft Graph API is primarily optimized for individual queries. For large-scale bulk operations, such as those required for archiving processes in Exchange Online, it is less suitable than EWS, which provides better support for such scenarios.
Resolution
For M365/Exchange Online, please primarily use Journal Archiving:
https://help.mailstore.com/en/server/Archiving_Emails_from_Microsoft_365_-_Modern_Authentication#Archiving_Incoming_and_Outgoing_Emails_Directly
This serves as the foundation for legally compliant email archiving.
If you also want to transfer the folder structure from the mailboxes, you can continue to do so using mailbox archiving. These archiving profiles can be run automatically in the background. Differences in runtime (EWS vs. Graph API) are therefore usually negligible.
Regardless, our team continues to work on potential optimizations.