How does Exchange determine that a OST file is old?

Copper Contributor

I have a user that is using two laptops to access the same Exchange account. One of the laptops is complaining that “Outlook is using an old copy of your Offline Folder file (.ost) ”.


The laptop with the issue has been turned off for a week. 


Deleting and recreating the .OST file each time this error appears is not feasible as the .OST file is sitting at 56GB and the user connects using WIFI not a WAN connection.


So how exactly does Exchange 2013 determine a .OST file is old? What can I do other than deleting the .OST file?


Any ideas would be appreciated.


Thank you.


Bart D. Hull 

3 Replies
Just to be sure, is the user using a roaming profile yes or no, and if yes, each laptop runs its own profile in Cached Mode on local OST copy -normally in AppData\Local?

@Michel de Rooij 


The users do have one 

Ost file in their appdata directory and are running in cached mode.


Any thoughts?


Thank you

Bart D. Hull

Phoenix, AZ.