Import PST to Office 365 Mailbox: PST Migration Tool for Windows

Upload PST to Office 365 with your own sign-in, without the admin route

Microsoft's own way to upload PST to Office 365 is made for moving many mailboxes.

Admin route

Network upload in Microsoft Purview

An administrator sends the files to Microsoft's cloud storage, maps each one to a mailbox and starts a job.

Needs the Mailbox Import Export role or a global admin
AzCopy upload, then a CSV mapping file of up to 500 rows
Microsoft advises PST files no larger than 20 GB

Your route

Open the PST, sign in, start

You stay on your own PC and use the same login as for your daily mail.

Writes into one mailbox, the one you sign in to
No command line and no mapping file
Some organizations ask for an administrator's approval first

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How to import PST to Office 365 with Email Migration Tool

Install the program and add your PST file

Download the Email Migration Tool and run the installer on Windows 10 or 11. The main screen is headed Import email files into a mailbox and has two panels, From and To. Click Add files in the From panel and pick the Outlook Data File (.pst). Only a PST works here. An OST cache file is rejected, and a PST that is open in Outlook is locked, so close Outlook first. The row shows Reading... and then the number of messages. A big file can take a few minutes to count.

Choose Microsoft 365 / Outlook.com in the To panel

Under Email service pick Microsoft 365 / Outlook.com and type the address of the mailbox. Addresses at outlook.com, hotmail.com, live.com and msn.com switch the service on their own. An address on your company's domain does not, so choose the service from the list. IMAP has to be turned on for the mailbox, or the program stops with the message IMAP is turned off.

Click Sign in with Microsoft

Press Sign in with Microsoft. Finish the sign-in on the Microsoft page and accept the consent screen. Back in the program the mailbox card reads Connected. On the left you get the tree Folders to migrate with a checkbox on each folder, on the right the list Where messages will go. Deleted Items and Junk Email of the PST come unticked. The Test button next to the sign-in checks the connection in 4 stages if something does not work.

Pick the destination and start the migration

Leave Destination folder as it is, or tick the merge option described below. Under Period you can limit the run to the last 12 months or to your own dates. Then press Start migration to import the PST file to Office 365. The progress screen counts what was moved, what was already in the mailbox and the errors. When the run ends you see a summary table, and Open migration log opens the full record of the run.

What moves from the PST into your Microsoft 365 mailbox

People who import PST to Office 365 first ask what they will find on the other side. They find their mail with its folder tree, and the list below names each part. A PST does not store a message as the original internet mail file. It stores fields. Email Migration Tool builds every message again from those fields and then places it in the mailbox. So this is a rebuild. It is not an exact copy. Calendar entries and contacts are not mail, so they are skipped, and so are tasks and notes.

The folder tree of the PST, without Outlook's service top levels
Each message goes up with its own date, not the day of the import
Attachments, including a message attached to a message
Both bodies, HTML and plain text, with inline pictures
Sender and recipients, Cc and Bcc included
Read or unread state and the draft mark
Follow-up flags, importance and categories do not come along

Download for Free

A PST migration tool that runs on your own PC

Reads the PST without Outlook

Email Migration Tool opens the Outlook data file with its own reader. Outlook does not have to be installed on the PC. The file is opened for reading and nothing in it is changed. The program takes the mail out in portions of 50 items or 64 MB and clears each portion from the temporary folder once it has gone up. Because of that it asks for about 256 MB of free disk space, however large the PST is. A broken item is reported as an error and the run goes on.

Microsoft sign-in in your browser

Sign in with Microsoft opens the Microsoft page in your default browser. You type the password there and the program never sees it. The access token stays in memory and is not written to disk, so you sign in again in every new session. Expect one surprise on the consent screen. Microsoft shows the app name Outlook Mail Merge. This sign-in is registered with Microsoft under that name, and the program window tells you so before you click. A work account may also need permission from your organization's administrator. For that case there is a ready dialog, What to show your administrator. It lists the application name, the permission it asks for and a consent link, and it has the button Copy for the administrator. Once the administrator approves the request, you sign in again.

PST folders land where you want them

Every folder of the PST becomes a folder of the mailbox. By default they go under Imported, in a subfolder named after the PST, and the hint in the window gives the reason. Everything lands in one folder that you can delete in one go. Tick Merge into the mailbox folders and the messages go straight into the folders with the same names, Inbox into Inbox. Before anything is written, each missing folder is marked as will be created.

Picks up after a break, no duplicates

A long run gets interrupted sooner or later. The program writes a journal to disk after every message, and when the connection drops it reconnects up to 5 times in a row. Stop it yourself or restart the PC, and the next launch offers to resume after the interruption with the Resume button. A message that is already in the destination folder is not sent a second time. If the PST itself holds two copies of a message, both are moved, because the program does not clean up duplicates inside your data.

Several PST files in one run

Add 2 PSTs or 12 to the From panel and start once. Each gets its own root folder, so mail from different jobs does not mix. PST is also only one of the inputs, because the same email migration tool takes MBOX and EML too.

Straight from your PC to the mailbox

When you import PST to Office 365 with this program, the mail goes from your PC to Microsoft's mail server over an encrypted IMAP connection. It does not pass through SoftOrbits servers. The only request the program sends to us is the activation of your license key. Before you start, the window shows an estimated time for the amount of mail you selected.

Four moments when a PST file has to go into Microsoft 365

Office workers carrying their desks into a new building while one archive box stays behind.

Your company moved to Microsoft 365

The switch was done for everyone over a weekend, and the new inbox was ready on Monday. Your local archives were not on anybody's list. They are still .pst files that you had been saving since the previous decade, and no one is going to carry them over for you.

A locked filing drawer and a hand holding a new key that does not fit.

New Outlook will not open your .pst on its own

Your archive is right there. A PC that shipped with Microsoft's new Outlook app alone cannot look into it. After the transfer its contents are in your everyday inbox, on the phone too.

A long queue at a single service window, and an empty chair where the clerk with the pass should sit.

The import job is stuck, or the Import link is missing

You tried the admin guide anyway. One thread on Microsoft's Q&A site describes a transfer that went fine and a job that then sat at Analysis in progress, at 0%, for days. A second one comes from somebody who could not locate the Import link at all. This program skips that whole service and talks to the mailbox directly.

An old tower PC on a cart by the door with a storage box of folders on top.

The old PC is going to be retired

The machine is on the replacement list and its drive will be wiped. Move the PSTs to the next computer and they are still files you cannot search from your mailbox. Load them into the mailbox instead. Then a thread from 2014 turns up in search beside this week's messages.

Who needs to import PST to Office 365 on their own

Employees with an old PST archive

You got a Microsoft 365 mailbox at your job, and you are a regular user there with no special rights. You also have five years of project mail in a PST. Sign in as yourself and send it up. If your organization blocks outside apps, the sign-in stops with Administrator permission is required, and you pass the ready details to IT.

Small office owners without an IT department

Three to ten mailboxes, and the person who knows computers is you. Go desk by desk. Each colleague signs in to their own mailbox, and their PST goes in. Loading a batch of mailboxes from one list is not something this program does. Did some of the staff keep mail in Thunderbird? The same program can import MBOX to Office 365, and that case has a page of its own.

Home users moving from classic Outlook to Outlook.com

For years Outlook collected your provider's mail over POP, so the only full copy of it is the PST on your PC. Now you want that mail in an Outlook.com mailbox that opens anywhere. A personal account goes through the same Microsoft sign-in page and the same mail server as a business one.

Trial and license for a PST to Office 365 migration

Run the whole route on your file and your mailbox before you pay.

For each PST file	Trial	With a license
Messages moved from each folder	25, the newest by date	All of them
Several PST files, folder choice, both destination modes	✓	✓
Time limit	None	None
The trial writes into your real mailbox. Its 25 messages per folder stay there. After you enter a key, press Move the rest: the program recognizes what is already in the mailbox and skips it. The key is bound to one computer.	Download	Buy now From $ 24.99

Buy now

From $ 24.99

Download

The trial writes into your real mailbox. Its 25 messages per folder stay there. After you enter a key, press Move the rest: the program recognizes what is already in the mailbox and skips it. The key is bound to one computer.

Email Migration Tool for Gmail and Office 365 - Import PST, MBOX and EML

Price

from $ 24.99 / month

Version

3.3

File Size

67.7 Mb

Last updated on

14/08/26

Trial: 25 newest messages from each folder of each PST file, no time limit

System Requirements

Windows 11/10/8.1/8/7 (32/64 bit)
Intel i3, AMD Ryzen 5 or above
4 GB of RAM or above
NVIDIA® GeForce® series 8 and 8M, Intel® HD Graphics 2000, Quadro FX 4800, Quadro FX 5600, AMD Radeon™ R600, Mobility Radeon™ HD 4330, Mobility FirePro™ series, Radeon™ R5 M230 or higher graphics card with up-to-date drivers
1280 × 768 screen resolution, 32-bit color
1 GB of free hard disk space or above

Frequently Asked Questions

How can I migrate PST files to Office 365?

There are three ways. An administrator can use Microsoft's network upload. The PSTs go to Microsoft's cloud storage with AzCopy, and a mapping file tells the service which mailbox gets which one. A user with classic Outlook can run the Import/Export wizard and choose the Microsoft 365 mailbox as the destination. The third way is a desktop program that signs in to the mailbox and writes the messages there, and Email Migration Tool is one of those. Choose by the count. Hundreds of files for many people is admin work. A few files for one mailbox you can do yourself.

How do I import a PST file to a shared mailbox in Office 365?

Short answer: not with this program. Long answer: Email Migration Tool writes only into the mailbox whose owner signs in. A shared mailbox is outside the current version, and so are archive mailboxes and batches of users. Ask your administrator about network upload instead. In that route the admin names the target mailbox for every PST in the mapping file, and the admin is the one to confirm that your shared mailbox qualifies.

How do I import multiple PST files into Outlook?

Microsoft's steps for Outlook's own wizard have you browse to one .pst file, so for the next file you run the wizard again. If the goal is the Microsoft 365 mailbox and not the Outlook program on this PC, you can add all the files at once in Email Migration Tool. They go up in a single run, each into its own folder, and you can untick parts of any of them before the start.

How do I import a PST file?

It depends on where the mail should end up. To see it in classic Outlook on this PC, open File, then Open & Export, then Import/Export, and choose Outlook Data File (.pst). To import PST to Microsoft 365 as mail in the cloud, use the four steps above. And if your new mailbox is at Google, you can import the same PST file to Gmail, which is covered on a separate page.

Why can't I open a PST file in Outlook?

Most often it comes down to which Outlook you have. Microsoft's help states that classic Outlook must also be installed for new Outlook to open PST files, and it lists the ARM version as not supported. Email Migration Tool gets the mail out with no Outlook on the PC, and after the import you read everything in the mailbox. It is not a PST viewer.

Is there a free way to import a PST file to Office 365?

Yes, and both ways come from Microsoft. It does not charge for network upload, and the Import/Export wizard is part of classic Outlook. But the wizard needs classic Outlook installed and set up with your account, and network upload needs an administrator. Email Migration Tool is a paid program. Its trial has no end date, and you can check the result on a folder or two of your mail before buying.

Why do I not see the Import option in the Microsoft 365 portal?

That option belongs to the admin route. Microsoft's requirements for creating import jobs name the Mailbox Import Export role in Exchange Online, or a global administrator account. A user on Microsoft's Q&A site could not find the link to the Import service and then ran into AzCopy syntax errors. If all you have is your own mailbox, the guide itself points you to the Outlook help page.

How big a PST can I import into Microsoft 365?

Email Migration Tool has no size setting of its own, and we do not state a maximum. The mailbox still has its limits. A message larger than the server accepts is skipped and listed in the report. The figures Microsoft gives are for its own import service only. For that service it recommends files no larger than 20 GB and says a mailbox takes in about 24 GB per day, adding that the rate is not guaranteed. Any item larger than 150 MB is skipped there.

Import PST to Office 365 with Your Own Microsoft Sign-In