outlook. .ost

our users are using outlook in cache mode so basically using .ost file

we cant change to online mode.

lately we are seeing growth in ost files on our file server where we are storing them

is there any thoughts or recommendations I can follow so that .ost file growth doesn't take place rapidly and thereby reducing disk space on file server

like telling users to mandatorily delete unwanted emails or any thing you can recommend
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JohnBusiness Consultant (Owner)Commented:
lately we are seeing growth in ost files on our file server where we are storing them

Do not do this. OST files should be on the local machine.  When you do this, you should easily be able to change to Online Mode..
timgreen7077Exchange EngineerCommented:
Wow, definitely don't put the ost file on remote servers. i'm assuming you can't change to online mode because of a GPO maybe, so set the GPO to cache only a certain amount of time like 30 days so that the file doesn't balloon on you. Really consider leaving ost files local to the user computer.
pramod1Author Commented:
cant change to local computer.

can u elaborate on gpo to cache only till 30days, u mean ost files will contain data upto last 30 days what about if user looks for email past 30 days?
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FOXActive Directory/Exchange EngineerCommented:
Question-  The users whose .ost files are bloating, do they have shared mailboxes in their outlook?
If so, verify if the shared mailboxes are added as "Open these additional mailboxes"  
If they are added in this manner you want to remove the shared mailboxes from there and
Add them as Email accounts
timgreen7077Exchange EngineerCommented:
Emails outside of the cache period is still on the exchange server and the users will click a link under the last cached email that says "Click here to view more on Microsoft Exchange", so it will query exchange for the remaining messages and load them into outlook for the user.

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JohnBusiness Consultant (Owner)Commented:
cant change to local computer.

Why?  That is where OST files belong by design and what is preventing you from getting to Online mode.

Why can you not use Correct Practice.
pramod1Author Commented:
What is the advantage of putting on local computer vis a vis a file server

Also regarding shared mailbox what is the difference between 2 methods as highlighted by fox

Add as an open these additional mailbox and as email account ?

Regarding times green we don’t have on premise exchange all mailbox are on 365 but we are using ost that is company policy I can’t change

Which link u are referring
JohnBusiness Consultant (Owner)Commented:
Outlook wants Exchange or a local connection. Putting a PST file or an OST file on a network connection can damage it.

You need to explain to the Company that the policy is Bad.
Edward van BiljonMessaging and Collaboration Technical Lead (Exchange MVP)Commented:
Please move the OST file locally and not on a server, I'm surprised you don't have slowness in outlook
Brian BEE Topic Advisor, Independant Technology ProfessionalCommented:
What is the advantage of putting on local computer vis a vis a file server
The whole point of a local cache file like an OST is just that, *local*. Otherwise you are creating a lot more network traffic. Twice as much, in fact. Once to synch the data with the Exchange server, then a second time to write it back over the network.

But to answer your question, set a size limit will force users to deal with their email. Email is not a place to store files that you want to keep. That *should* be done with a file server.  Alternatively set up a proper Exchange archive.
pramod1Author Commented:
When you have shared mailboxes opened as additional mailboxes their data is added to the .ost of the user's mailbox. If you add the shared mailboxes as seperate email accounts they will have their own .ost files.   so in both case either .ost is getting added to user mailbox or having their own ost looks to me the same

kindly clarify
JohnBusiness Consultant (Owner)Commented:
Each user will have their own OST file so far as I know.
timgreen7077Exchange EngineerCommented:
When you have shared mailboxes, you can set the options not to download the shared folders, and that will keep the shared mailboxes from affecting your ost file.
Brian BEE Topic Advisor, Independant Technology ProfessionalCommented:
Again it comes down to the fact you are using the product in a way that is not supported. It's hard to work around that.
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