Office 365 Backup Tool: Migrate Microsoft 365 Mail to PST

How to download and use the Office 365 Backup & Migration Tool

1. Sign in with Microsoft

Download the Office 365 Backup & Migration tool and start it. The button that normally says Open PST opens the Microsoft login page inside the window instead. No Azure app registration to do first.

2. Pick folders and a date range

The folder tree of the mailbox appears with checkboxes, and the message list next to it has a Size column, so the heavy folders are visible before you start. Tick the folders you care about. The date filter runs on the server, so the list in front of you is exactly what will land in the file.

3. Look before you download

Click a message and it opens in the preview pane, with remote content left unloaded. Two minutes here save a long download of the wrong folders, and you can see straight away that the mail the program reads is the mail you expect.

4. Get your PST file

Choose where to save and start the backup. Large mailboxes take hours, and the program keeps a resume point next to the file. If the connection drops, the next run continues from there. When it finishes, open the file in Outlook through File, then Open and Export, then Open Outlook Data File.

Why back up a Microsoft 365 mailbox to PST

Every year of your mail, not the recent slice

The whole point of an archive is the message you will want in ten years. A contract from 2014, a receipt that settles a warranty argument, the thread where somebody agreed to something in writing. Age is exactly what the built-in export tends to lose, and people find that out late, when they go looking for those years. You name the years you want, and Office 365 Backup & Migration Software brings down exactly those.

Download for Free

A copy that outlives the account

Accounts end for administrative reasons rather than technical ones. Microsoft closes an account that nobody has signed into for two years, universities publish deletion schedules for graduates, and an employer can switch your access off on the last working day. Most people arrive here with such a date already in the calendar. A PST kept on your own disk remains readable long after the account it came from has been closed.

Download for Free

One person with one mailbox

Backup for Microsoft 365 is normally sold to whoever administers the tenant. A console in the browser, an administrator to run it, a seat for everybody in the company. That shape of product is right for an IT department and wrong for one person with one mailbox and deadline, which is the situation almost nobody in this category writes for. On a personal outlook.com or hotmail account you are not asking anyone's permission here.

Download for Free

Permission you can hand back

Letting an unfamiliar program at your correspondence is a fair thing to hesitate over. The access is not permanent. Microsoft keeps the switch on its own side, so on the day your copy is finished you revoke it in the app permissions of your Microsoft account, and we are not part of that step either.

Download for Free

What the Office 365 Backup & Migration tool does

Sign-in instead of a file

There is no input file to pick and nothing to drag into the window. The source is the mailbox itself, reached over Microsoft Graph with a read-only mail scope. After the sign-in the address of the mailbox sits next to a Sign out button, so you always see whose mail is on screen.

The mailbox in front of you

Folder tree on the left, message list in the middle. On the right is preview of the letter you clicked. It does not pull remote content, so tracking pixels in old newsletters stay unfired, and the status line says so plainly. You can read through the mail before you decide to save it.

Date range that reaches the server

The date filter is applied by the mailbox, not by the program after downloading everything. Ask for 2019 to 2021 and only those items travel over the wire, which allows you finish sooner on a mailbox holding tens of thousands of letters.

Made for long runs

The pace is set by Microsoft's own request limits, not by your CPU. In our test the tool pulled 200,000 messages in 3.5 hours without losing one, and a run that was killed halfway picked up where it had stopped. When the server asks to slow down, the window says it is waiting instead of looking frozen.

Attachments byte for byte

Attachments go into the PST unchanged, verified up to 224 MiB in our tests. Before the first letter is written the Office 365 Migration tool checks the destination and warns when the free space is short, which is better than finding it out when the file is half written.

Mailbox item	In the PST file	Notes
Folder tree	Yes	Subfolders keep their nesting and their names
Subject, From, To, Cc, dates	Yes	Sent and received dates stay as they were, not the date of the backup
HTML body and formatting	Yes	The letter opens in Outlook looking like the original
Attachments	Yes, byte for byte	Checked up to 224 MiB per attachment
Read and unread state	Yes	An unread letter stays unread in the file
Contacts, calendar, tasks	No	Mail only in this version
Shared and delegated mailboxes	No	Only the mailbox you sign in with; the Microsoft 365 online archive is not read in this version

Email Backup & Migration Tool for Microsoft Office 365 and Outlook

Languages

File Size

20 Mb

Version

1.0

Last updated on

02/07/26

$ 39.99

🖥️ 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

❓ Does Microsoft 365 back up my mailbox for me?

No, not in the sense of a copy you own. Microsoft keeps your mailbox available and recoverable inside its own service, under retention rules an administrator sets. That is not the same as a file in your hands, and there is no button in Outlook on the web that hands you the mailbox as a PST on demand. A local copy is something you make.

❓ Will I get all my mail, or only what Outlook has cached?

All of it, within the date range you pick. The reason this question exists is that the export inside Outlook works from the local .ost cache, and that cache holds a window of recent mail rather than the mailbox. People end up with a PST that starts in 2024 while the webmail still shows 2018. Office 365 Backup & Migration tool does not read the cache at all. It walks the mailbox on the server, folder by folder, and the closing report accounts for every message it planned to write, naming the number of anything it could not.

❓ The export option is greyed out in the new Outlook. Can I still get a PST?

Yes. The greyed-out item is a common complaint about the new Outlook, and it is one of the reasons this program exists on its own. It does not use Outlook's export, and it does not need Outlook installed to write the file. It signs in to the mailbox itself. You do need Outlook, or any PST reader, to open the result afterwards.

❓ What permissions does it ask for? Can it delete or send mail?

It asks to read your mail, nothing beyond that. The sign-in requests a delegated read scope for messages, which lets the program list folders, read letters and download attachments. No write or send scope is requested, so it cannot delete a message or send one from your address, and marking or moving are equally beyond it. The consent screen from Microsoft spells out what is being asked before you agree.

❓ Where does my sign-in go, and how do I take the access back?

The sign-in happens between you and Microsoft, and the token that comes back stays in the memory of the running program. It is never written to a file or to the registry, so closing the program ends the session - that is why you sign in again next time instead of finding yourself already logged in. Nothing about the session or the mail passes through any server of ours. To cut the access off for good, open the security settings of your Microsoft account, find this application under app permissions and remove it.

❓ How big can the PST file get?

In Outlook 2016 and newer a PST file is allowed to grow to 50 GB by default, and from about 47.5 GB Outlook stops letting new items into it. Older versions allow much less. For a mailbox bigger than that, back it up in date ranges into separate files, which is what people do by hand anyway. Plan free space by roughly the size of the mailbox, and keep the destination out of an NTFS-compressed folder, where small messages cost more space rather than less.

❓ Are attachments saved exactly as they were?

Yes, unchanged. That includes text files, where a single trailing line break is the kind of difference easy to lose in conversion. The largest attachment in our test was 224 MiB and it came out identical. Above that the program stops with a message instead of writing a truncated file. Exchange Online caps a message at 150 MB anyway, so the tested range covers what a mailbox is able to hold.

❓ Can I keep the backup on an external drive or in OneDrive?

An external drive is a good destination. Plenty of people back up Outlook emails onto one and keep the drive in a drawer. Point the program at it and the file is written there directly. A cloud-synced folder is a different matter. Choose a folder that OneDrive or Dropbox keeps in sync and the program warns you, because the file you just pulled out of the cloud would immediately begin uploading back into it. Write it locally first. Copying it into cloud storage afterwards is then your decision rather than a side effect.

❓ My work Microsoft 365 account asks for administrator approval. What now?

Your organization decides that, not us. By default a user may consent to an application reading their own mailbox, but a tenant is allowed to restrict this, require admin consent, or turn user consent off altogether. If your sign-in ends in a request for approval, one of those settings is why, and only an administrator can lift it. On a personal outlook.com account the question does not come up.

❓ Does it move mail from one mailbox into another?

No, it does not migrate mail from one mailbox into another. The direction is one way, from a live Microsoft 365 or Outlook.com mailbox into a PST file on your computer. That covers migrating your mail out of the cloud and onto your own machine, which is why the tool is also described as a migration tool for Microsoft 365 and Outlook. Writing messages into a second mailbox is not something this version does, and the read scope it asks for could not do it in any case.

❓ Does it work with Gmail, or on a Mac?

Neither, and it is better to say so before you download anything. The program is Windows software, and the mailbox it reads has to be a Microsoft one. Microsoft 365 and Office 365 count, and so do the free Outlook.com, Hotmail and Live addresses. Gmail and Google Workspace are outside this version. For mail that already sits in files on your disk, our other converters take MBOX, EML, MSG, OST and EDB into PST.

Download Office 365 Backup & Migration Tool for Outlook and Microsoft 365

How to download and use the Office 365 Backup & Migration Tool

1. Sign in with Microsoft

2. Pick folders and a date range

3. Look before you download

4. Get your PST file

Why back up a Microsoft 365 mailbox to PST

Every year of your mail, not the recent slice

A copy that outlives the account

One person with one mailbox

Permission you can hand back

What the Office 365 Backup & Migration tool does

Sign-in instead of a file

The mailbox in front of you

Date range that reaches the server

Made for long runs

Attachments byte for byte

Who needs Office 365 Backup & Migration Tool

Leaving a job or a university

Owners of an old Outlook.com or Hotmail mailbox

Working on a company Microsoft 365 account

What lands in the PST file

🖥️ System Requirements

🙋 Frequently Asked Questions

Other email and Outlook converters

Convert email to Outlook PST

Convert email to PDF

Convert Outlook mail to other clients

Repair a damaged Outlook file

Rate Email Backup & Migration Tool for Microsoft Office 365 and Outlook

Risk-free download