Constant Calendar Sync issues and 25GB+ *.ost file size?

[rhallmcp]

We are running O365 w Email, and are running into a constant flow of calendar sync complaints in outlook. These users are all typically Admin Assistants and delegates for multiple Executives, and are always changing schedules and cancelling meetings for the users they are delegates for. They are noticing consistently that they will change a meeting, and it will not update on the users calendar/phone/laptop for an extended period of time. They also notice this for another person in the office that is a delegate for the same user.


Something to point out is that these delegates all have a local *.ost file in excess of 25GB. Since this is hosted O365 email server, if you remove the *.ost and force it to rebuild, it can take a week or more to rebuild.


Any ideas or suggestions?

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