Know Why OST File is Larger than the Mailbox Size?

If we look at the OST file’s size, then we would find that it is not really representing the mailbox size. Mostly, the mailbox won’t make up a big portion of this OST file. But there are more items stored inside it. That can be bigger too generating problems for users such as the Outlook OST file being larger than the mailbox.

While using Outlook 2013 or 2016 version, the OST file could possibly be smaller than the mailbox itself. Email items stored inside an OST file depend upon the type of account used, Exchange/IMAP account, or connected to Outlook.com mailbox through Outlook’s Hotmail-Connector or through EAS or Exchange ActiveSync.

Expert Tip: When users store any data in the folders that don’t sync with the email server, then it is always suggested to make backups of those folders via Export instead of backing up of OST file. The reason is, unlike PST files, OST files cannot be restored directly without using a good 3rd- party tool which will enable you to split large size OST File into smaller parts.

Download Now Purchase Now

Reasons: Why OST File Bigger Mhan Mailbox Size

Following are the data Usually Stored in the OST File of the Exchange Server Account that can make the Outlook OST file size is larger than the mailbox.

• Mailbox data

1. Email
2. Tasks
3. Calendar
4. Journal folders
5. Notes
6. Contacts

• Hidden items & other “overhead” found in the PST file
• Public-Folder Favorites
• Shared folders that are of other additional mailboxes, which have been linked to Exchange’s account
• OST files of Outlook’s Hotmail-Connector/EAS/IMAP account

Important Note:
If any user stores any data in those folders that don’t sync with the email server, then it is suggested to take backups of those folders through an Export rather than backing up of the OST file.

Ways to Reduce Outlook OST is Larger Than The Mailbox

#1. Recreate a Fresh File

After some major cleanup operation, the user can either choose to let the Outlook program recreate the OST file rather than compact that, or users can also wait for automatic compression to happen. For doing this

• Renaming of OST file has to be done
• Rename to .old
• This has to be done when the MS Outlook program is closed
• On restarting MS Outlook, the mailbox gets re-cached into a new OST file which can help users to resolve issues related to Outlook OST file too large.

#2. Another Method Is By Syncing Filters

When users are having any big-sized folders or Outlook OST file is larger than the mailbox size, then they can set Synchronization-Filters for determining what would get synched & stored inside that OST file.

#3. It Is Even Possible to do It by Syncing Slider

In Outlook 2013 & 2016 versions, users can make use of the Sync-Slider. When the OST file is bigger than the mailbox size for only caching more-recent email items instead of the whole of the mailbox.

#4. Try Disabling Caching of Shared Folders

If the user doesn’t need any offline access to his shared folders and doesn’t access those on a regular basis too, then he/she could possibly disable the cache option for shared folders generally or not cache the shared email folders.

#5.  Disabling Caching of Public Folders Favorites

When the Outlook OST file is larger than the mailbox. Same as shared folders’ caching, users can even choose to disable the option for caching Public-Folder-Favorites.

#6. Remove Some of the Public-Folder-Favorites

When the OST file is bigger than the mailbox size. Instead of disabling this option totally, users can even try removing some of their Public-Folder-Favorites or can select only a few sub-folders rather than reducing the amount of data that is being cached.

#7. Gmail Duplication Method Can Also Be Tried

While using Gmail’s account, the email items can get duplicated because of the folders users have subscribed to. This even applies to MS Outlook 2010 version and previous ones that store IMAP cache in a PST file.

Conclusion

When an Outlook OST file is larger than the mailbox, reducing the OST size might not be needed always in the first place; and even if it is needed, it is not always very easy. While using any reasonably modern machine and using Outlook-2007-SP2 or any later version, then OST file bigger than mailbox size as big as 10GB size and you would still not notice any such performance hit.

But nevertheless, allowing it to grow bigger and bigger in size pointlessly is also not the way to work either. You can create a backup by converting the OST file into PST format.