How to import a large .pst file into Outlook classic

[zman12255]

The issue I am having:  

I exported a client's email inbox to a .pst file that is about 48GB, then imported it into Outlook on another PC. Hundreds of folders remain after the import, but the email contents of alot of the folders are empty, like they didn’t all import 

Questions:  

whats the best way to import large amounts of email? 

is there a 3rd party tool to do this? 

Due to the client's needs, using another email program isn't in the books 

[Nick H. Supervisor]

48GB?! That's insane! But I digress.

Does the client still have access to the original emails? Or have they been removed since the .pst file was created?

[Martog]

Oof, that's a large file.

Did you import it into Outlook or just add it as another PST file? I've done that before and just remove the default PST file after making the new one the default.

Was this done from Outlook on another PC? If so the PST could have just been copied.  Also is this POP3, IMAP or something else?

[binaryzero]

Do yourself a favour and move your client to a modern email solution, Exchange Online. Couple bucks a month for a mailbox, eliminate pst files.

It's 2026, pst files were considered legacy a decade plus ago.

[zman12255]

On 18/02/2026 at 19:07, Martog said:

Oof, that's a large file.

Did you import it into Outlook or just add it as another PST file? I've done that before and just remove the default PST file after making the new one the default.

Was this done from Outlook on another PC? If so the PST could have just been copied.  Also is this POP3, IMAP or something else?

I used the import feature. Thanks for all the responses! I talked the client into using another solution 

[Somnus]

On 19/02/2026 at 01:21, binaryzero said:

Do yourself a favour and move your client to a modern email solution, Exchange Online. Couple bucks a month for a mailbox, eliminate pst files.

It's 2026, pst files were considered legacy a decade plus ago.

Where can one get an exchange account for a few bucks a month?

[Steffan]

If your customer has Exchange (either on-prem or EXO), you can import the PST file directly to their mailbox. 

https://learn.microsoft.com/en-us/exchange/recipients/mailbox-import-and-export/import-procedures

https://www.alitajran.com/import-pst-office-365/

[binaryzero]

On 17/04/2026 at 04:37, Somnus said:

Where can one get an exchange account for a few bucks a month?

https://www.microsoft.com/en-us/microsoft-365/exchange/compare-microsoft-exchange-online-plans

[Nick_swe]

In my experience importing large PSTs especially 50GB can cause exactly these problems. If you must import it into a mailbox it’s safer to split the PST into smaller chunks first.

[Steven P. Administrators]

On 19/02/2026 at 16:32, zman12255 said:

I used the import feature. Thanks for all the responses! I talked the client into using another solution 

You can also convert the PST into a mail backup with MailStore https://www.mailstore.com/en/ I use it to manage the limited storage I have on Zoho.

This way the client will have a backup of those emails in a dedicated program.