OST files are the core of Outlook. It stores replica of all the outlook mailbox data present on Exchange server. Just like other files, ost too has predefined maximum file size limits. If the size of your ost file grows beyond the predefined limit, then it becomes difficult to manage it and later on it can cause severe ost file corruption and data loss situations.
When a mailbox grows in size or the number of mails increases in the mailbox, then it becomes difficult for the user to manage them easily. For an easy email management, he may choose to delete the unwanted items from the mailbox or send those mail items to other folders.
When you delete an item from the mailbox it goes to Deleted Items folder. It still occupies space on the hard disk. Later on, the item can be deleted from the Deleted Items folder. This type of deletion is called soft deletion. But if you delete an item from the inbox by pressing SHILT+DEL it is deleted directly without being moved to Deleted Items folder. This type of deletion is known as hard deletion.
If the OST file grows up to critical size, then becomes more prone to corruption. To keep the ost size into limit you must keep removing the unwanted items from the ost file from time to time. After deleting the unwanted items from an OST file, perform ost file compaction. You can also choose to run automatic compaction.
From the above discussion, we can conclude that, in order to optimize the ost file size:
- Delete the unwanted mailbox items from different folders
- Empty the Deleted Items folder permanently.
- Compact the ost file
In order to compact the ost file, follow the given steps:
- To Clear offline items: simply go to menu ->Folder List -> Inbox. Then Open properties and select the option”Clear Offline Item”
- Go to Tools -> E-mail accounts ->View or change existing e-mail accounts
- Click Next
- In the Outlook processes e-mail for these accounts in the following order list, choose the option Microsoft Exchange Server
- Click Change.
- Click More Settings -> Advanced tab -> Offline Folder File Settings then click Compact Now.
There can be other solutions to deal with the OST related issues:
- Run Outlook in safe mode: If you are facing problems while working with outlook then, try running it in safe mode. See whether this resolves the problem or not.
- Renaming and rebuilding the OST File: Sometimes your OST file starts troubling you while performing mail operations such as: opening, composing, sending, receiving and deleting mails. In such situation, only Renaming and rebuilding the OST File is enough to get the issue resolved. Juts rename your previous OST File, restart outlook and let it create a new OST file itself.
- Rebuild your Outlook profile: There can be two cases: you are using Outlook with POP account or using Outlook with Exchange server /IMAP account. In the first case, Export your data file and delete the POP account. Recreate the POP account and then re import the exported data file. In case of Exchange server /IMAP account, just delete the profile and re-add it.
- Disable add-ons: There can be some conflicting add-ons installed in Outlook that can hamper its functioning and leading to performance slow down. Disable such suspect add-ons and see if this enhances the speed of outlook operations.
- Disable antivirus/anti malware or firewall: If your Outlook has been working slowly, then the installed antivirus/anti malware or firewall applications can be one of the common reasons. Just try temporarily disabling them and see if this improves the Outlook performance.
- Archiving: Archiving your old outlook file data is a good way of emptying the extra space occupied on server. You can copy the archive file and save it to any desired location.
- Reset navigation pane: Sometimes the customizations made to the Outlook navigation pane can lead to outlook slowdown. In such case you need to reset the navigation pane. To reset navigation pane, run: outlook.exe /resetnavpane.
- Manage outlook data files: if you have multiple large sized outlook data files or archives on the server. Then, it’s better to move these archives to some local drive, in order to reduce the server load.
How to fix OST synchronization issues?
Microsoft provides ScanPST.exe to deal with the OST file corruption related issues. It checks for the ost/pst file structure integrity. It scans the files, diagnoses the errors, then resolves them.
If there are some OST file synchronization related issues, then ScanOST.exe (OST Integrity Check tool) proves to be useful. It is handy while you are facing OST to Exchange synchronization issues. It checks for discrepancies and differences between the Exchange data and the ost file data. This scan information can be found in the scan log folder under your Deleted Items folder.
Fix OST synchronization issues in Outlook 2010 or later versions:
In Outlook 2010 and later versions, Scanost.exe tool is not available.
So, if you are facing OST synchronization issues in Outlook 2010 or later versions, then delete the OST file and let outlook recreate it and synchronize it after downloading data from Exchange server.
If your OST file contains some local data that isn’t present on the Exchange server then export the OST file data to pst file. Delete the ost file and create a new one. Now, the exported pst file data can be imported back into the newly created ost file. If there are some duplicates in the pst file you can choose to prevent it from being imported to the OST file by choosing the option’ Do not import duplicates’.
The step by step process is given below:
- Export the ost file data to a pst file
- Delete the old ost file
- Create a new ost file.
- Go to File > Open>Import. Then choose ‘Import from another program or file’
- Click next
- Select Outlook data file (.pst), and then click next.
- Click browse to select the pst file that you have exported in step 1
- Choose the option ‘Do not import duplicates’ to avoid importing duplicate copies of the same item.
- Click Next.
- Select destination folder where the pst file data is to be imported. Click ‘Next’ to proceed.
- Finally click finish to accomplish the import procedure.
What if the scanost.exe/ OST Integrity Check tool fails to resolve the OST file synchronization related issues? In such situation you require some OST to PST Converter software that can let you export your ost file data to pst format. And later on, the converted pst file can be imported into outlook and you can continue to work with it.