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"ost" and "pst" files

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when you click "File", then "Data File Management", and click "Open Folder" , it shows ".ost" file 8GB while there is multiple ".pst" files with different size (1GB, 2GB,etc..) i wonder which file to select for archiving as a backup in case of computer crash...

thank you

All Replies
  • Hi  NA,

    Offline Outlook Data Files (.ost) are copies of your Exchange information, When we enable outlook cache mode , outlook will automatically generate this file. About other pst files, you can directly open it by outlook and check if it is useful for you. My suggestion is you’d better create a new pst file to back up your data.

    To create a new PST file in Microsoft outlook 2010

    Please follow the below steps

    1.Open Outlook 2010.

    2. Go to the Ribbon and select the Home tab.

    3. In the New section, select New Items.

    4. When the menu appears, select More Items followed by Outlook data file.

    5. When the Create or Open Outlook Data File window appears, browse to the location where the file is to be located. Go to the File name text box and input the desired name for the file. If you wish to add a password to the file, check the Add Optional Password check box.

    6. Click the OK button.

    To Export Outlook items to an Outlook Data File (.pst), please see link below:

    Best Regards,

    Jacky Ding

  • dear Jacky, thank you so much but i have outlook 2007? please advise if this is possible?

  • Hi NA,

    Sorry for incorrect information with outlook version.

    To create a new PST file in Microsoft outlook 2007

    1. Click File and select Data File Management.

    2. Under the Data Files tab, click Add.

    3. Select the desired type of data file.

    4. Click OK.

    5. In the new window, browse to the location that the file will be saved.

    6. In the File name box, type the name for file.

    7. Click OK.

    8. In the Create Microsoft Personal Folders dialog box, type the name that will be displayed in Outlook for the data file in the Name box.

    9. Click OK.

    10. Click the Close button in the Account Settings dialog box.


    To Export Outlook 2007 items to a Personal Folders file (.pst)

    Best Regards,

    Jacky Ding


  • thank you jacky, i am confused since your colleague :Alexandru Dionisie" is telling by saving "ost"

    pls advise

  • Hello Guys

    Just Try This Application & Save OST File As PST Format :

  • OST Repair -


  • Try SysTools OST Recovery Tool to Convert OST File in PST Format

  • SysTools OST Recovery  Tool best option to Pair Corrupt OST File

  • dear,

    my question is simple i want to backup my emails/calendars/notes/contacts... in 1 single file in a folder on my desktop and this file will be updated each and everytime i open then close my outlook 2007

    please advise how if any? thank you very much

  • Hi NA,
    you can create a new PST file and use this pst file as new item default location.The steps below are how to point Outlook to your new personal folders file:

    1. Open Outlook.
    2. On the Tools menu, click Options.
    3. On the Mail Setup tab, click the E-mail accounts button, even if you do not have an email account specified.
    4. On the Data Files tab, click Add.
    5. Click Office Outlook Personal Folders File (.pst), and then click OK.
    6. Find the  location of your .pst file, and then click OK two times.
    7. Click Set as Default.
    8. If this is your default e-mail delivery location, you will receive the following message:
      You have changed the default deliver location for your e-mail. This will change the location of your Inbox, Calendar, and other folders. These changes will take effect the next time you start Outlook.

    about how to create a new pst file in outlook 2007 ,you can refer above reply.


    Best Regards,
    Jacky Ding

  • thank you Jacky, i am confused because of one thing: when i set up the office 365, the account  automatically generated an "ost" file not pst and ost is so large

    i am concerned if i loose any data if i use pst instead of saving ost?

  • Hi NA,
    The data will be safe as long as the pst file is safe. So please protect the pst file from breaking.
    The link below will give you more information about difference between pst with ost.

    Best Regards,

    Jacky Ding

  • Hi NA,

    How are the things going?

    Jacky Ding

  • Hello,

    There are several commercial tools available that can convert OST file to PST and make them accessible for further use. Kernel for OST to PST  Converter Tool one of them you can try it from here