Hello @thomas ,
Thanks for your query.
1.Is there any error message when the ost files corrupted?
2.What's your registry configuration of fslogix profile container and office container?
3.Did you enable the Cached Exchange Mode? If so, the maximum default size of an OST file is 50 GB, and An OST file will be 50-80% larger than what is stored in the mailbox. https://stealthpuppy.com/fslogix-containers-capacity/
https://video2.skills-academy.com/en-us/outlook/troubleshoot/installation/cached-exchange-mode
WHY IS FSLOGIX O365 CONTAINER ESSENTIAL WHEN USING OFFICE 365?
: https://virtualwarlock.net/why-is-fslogix-o365-container-essential-when-using-office-365/
Ongoing OST corruption with cached Exchange mode in Outlook 365
: https://community.spiceworks.com/topic/2296194-ongoing-ost-corruption-with-cached-exchange-mode-in-outlook-365
Best regards,
Leila
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