ost file sizes

Hi

One of my users outlook 2010 machines was running awfully slow, hanging and sometimes crashed today.  In the end i removed all the files from c:\users\user\appdata\local\microsoft\outlook\ and fired outlook online again to recreate the files.  This old ost file was 9.5gb, the new one is 4gb.
What reason has it stayed so large.  Her mailbox was 2.5gb and another shared mailbox was 2gb.  
Does the ost files compresses itself automatically?

Thanks
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CHI-LTDAsked:
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Niten KumarConnect With a Mentor Principal Systems AdministratorCommented:
If you have two mailboxes configured under the same profile then both downloaded mails to the same ost file and that is why the ost file was so big.   This depends on how you apply Full Access Permissions to the shared mailboxes.

Suggestions to take to solve issue for good:

1.  Remove profile and delete all files from c:\users\user\appdata\local\microsoft\outlook\
2.  Log off the user
3.  Remove the Full Access permission from the shared mailbox.
4.  Open EMS and enter the following command
Add-MailboxPermission -Identity XXXXXXX -User 'YYYYYYY' -AccessRight FullAccess -InheritanceType All -Automapping $false

Open in new window

     XXXXXXX - is the shared mailbox
      YYYYYYY - is the user who will Full Access Permissions

5.  Give about 5 to 10 mins fro permissions to apply.  Ask the user to login and recreate the profile.


You can refer to the following article for more information:

https://technet.microsoft.com/en-us/library/hh529943.aspx?f=255&MSPPError=-2147217396
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Lisa Hendrickson "CallThatGirl"Connect With a Mentor MS Outlook ExpertCommented:
I assume IMAP? Gmail or ???

I see this all the time when I help clients, usually it's just corrupted (why it broke too) and now that you got a fresh download, that is the actual size of the IMAP server mailbox.

FYI, I always keep a copy of the OST file if I can, in case of data missing or some calendar was in there/contacts too. Outlook is sneaky.
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rindiConnect With a Mentor Commented:
OST files don't go smaller in size, even if you delete mails etc. The best thing to do is not to use OST files, or just delete them, as they will rebuild automatically in cached mode. Normally though the file shouldn't be needed, unless your internet connection always drops.
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Niten KumarPrincipal Systems AdministratorCommented:
Are you running on Exchange 2010 and does the user mentioned above have two mailboxes?  Then there should be two new ost files created when you recreated the profile.
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Edwin HofferTechnical ExpertCommented:
Dear User

If your OST file size gets too large then you can crop your OST file. I found article that will help you in resolving your thread. There are several reasons & failures resulting in oversized OST file like:
1. Data storage devices.
2. Network connection failure.
3. Sudden power failure.
4. Improper maintenance of files in the OST file.
So with the help of this blog you can Crop your Oversized OST if OST file size gets too large

Thanks & Regards
Edwin Hoffer
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CHI-LTDAuthor Commented:
Exchange 2010 hybrid with 365.
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Marshal HubsConnect With a Mentor Email ConsultantCommented:
Please check this article to overcome oversized OST file issues.
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