Outlook PST Export Question


Hello I have a question about how Outlook handles exporting a PST file for a very large mailbox. If I were to export a attached shared mailbox that is 103GB big, does Outlook portion it out in 10GB chunks the way it does by using the Exchange "New-MailboxExportRequest" does? I am having a hard time getting our Exchange Online admin to fulfill this request so I am wondering if I have it added to my account with Full Access can I just export it myself and have it create consecutive .PST files until the entire mailbox contents are exported? Not having luck Googleing this.


Thanks in advance!

8 Replies

@charlie4872   The Unicode PST file created by Microsoft Outlook 2013 or 2016 has the maximum size limit of 50 GB. So if you're looking for a way to import a PST file whose size is around 100 GB, you need to increase the Outlook mailbox size limit.


Try this below link step by step on how to increase the limit....

Thanks for the response @PDostiyar What I am looking to do is Export a .PST and am wondering if it will create separate .PST files when exporting a large mailbox from Outlook. I know when doing the "New-MailboxExportRequest" powershell command in Exchange online it creates 10GB .PST files until the whole mailbox is exported. I just dont know if Outlook does the same thing.

best response confirmed by charlie4872 (Contributor)

@charlie4872 the bad news is no, Outlook will not be able to split the .PST, it just exports as a single .PST


You could look to use a eDiscovery and export a date range to then get the pst size down.


I know third party tools also can do this though have not tried these my self so cant recommend one

Thanks for the reply @Willjmoo So Outlook would just export on large 100GB .PST file that would probably be unusable correct? My thinking is if I were to do this in Outlook I would just select individual folders If needed and that would be one workaround to get smaller .PST files. Otherwise I agree the best way to do this would be to have the Exchange admin team do the export. Just wanted to confirm.



no problems@charlie4872 


a 100GB .PST would not be nice to work with, you can like you say export smaller chunks but this will take a long time, if the Admin can do it via an ediscovery that would be best


good luck

Hi, @charlie4872

I know that it is difficult to migrate large size PST file to other email clients or file format. Hence, it is advised to split single large PST file into multiple smaller PST files for efficient migration of Outlook data. I recommend you using PST Exporter tool to export your PST files to with ease and split in different PST files. This professional tool migrate your Outlook data without losing any data.

Hi @charlie4872 ,

While working with Outlook from past 10 years, I had faced these types of issues in past years. Now let me share few tips and tricks to export PST from Outlook.

In case you have large mailbox data, as you had mentioned about 103 GB right? Go to Open and Export menu and follow the instructions till the window when asked to select folders.

You can select or export mailbox folder separately each time. May be it will minimize the data size.

Or you can use any PST Splitter Tool that could help you in splitting large Outlook data into small PST files. 

Comment or approve my answer if it helps you.



Also Check Out :


The above will help you to reduce your mailbox size.