OST Files and Sizes

[ColinA]

Hi, I have come across a problem with Outlook 2010 and it is to do with the size of the local OST file..



As an example, I have a user who has his own mailbox which is 5GB, he also has access to 3 other mailboxes, Helpdesk 5GB, Customers 5GB, Vendors 5GB...

It therefore follows the local OST file should be approx. 20GB...

I have found that the OST file never gets smaller, even if emails are deleted, it only grows...

My understanding is that the OST file will not shrink unless you adopt one of the following methods of shrinking it

1. Put a setting in the users Registry that will start the shrink on closure of Outlook
2. Manually Compact it thru FILE, ACCOUNT SETTINGS etc, and select Compact on the OST file
3. Leave the machine on overnight with Outlook running and an inbuilt process kicks in when the machine is idle that will start the Compact process

These are not great options.., leaving 10-15 machines on every night doesn't go well with the bosses..., and manually running the Compact takes ages.. Setting the key in the registry creates other problems as users sit there for ages waiting for the Compact process to complete.., again, not good..

My problem is that these OST files are getting massive, up to 49GB at which point the users start getting slowness and not responding type messages..., and in turn I have users after me to resolve it..

At the moment, my only option seems to be to rebuild their OST by renaming the old one and starting Outlook again.. I do this at weekends as it gets me round the problem but I need a better solution...

Does anyone have any ideas how to sort this...?

We user Office 365 as our email system...