Outlook Duplicate Remover Outlook Duplicate Remover
4.5 · 1140 votes

Download Outlook PST Duplicate Remover Software

Outlook Duplicate Remover clears duplicate emails out of Outlook PST and OST files without touching the original. The unique messages go to a fresh PST you choose.

   
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Windows 11 / 10Free trial, no sign-up
Outlook Duplicate Remover Screenshot.
Duplicate emails come from IMAP accounts, a mailbox synced on two computers, or a PST you imported twice. Outlook's own Clean Up only looks inside one folder at a time. The copies sitting in Sent and Archive go unnoticed. Outlook Duplicate Remover reads the PST or OST file directly, on your PC, with no Outlook running. It never edits that source file. Instead it groups the duplicates by rules you set and writes a fresh PST that holds one copy of every message, whether you are on Windows 11 or cleaning an old export from Outlook 365.

How to download and use Outlook PST Duplicate Remover Software

Open your PST or OST.
1

Open your PST or OST

Point the Outlook PST Duplicate Remover Software at any Outlook data file. The folder tree loads with checkboxes, and each message shows its subject, sender and date, alongside its size.

Choose folders and match rules.
2

Choose folders and match rules

Tick the folders to scan, then decide what makes two emails a duplicate. You can match on Subject, sender, body text, and more. Cross-folder scanning is on, so Inbox and Sent get compared together.

Pick which copy to keep.
3

Pick which copy to keep

Keep the first, oldest, or newest message in each group, and set the output folder for the cleaned PST. Turn on the backup file if you want a rollback.

Run and check the report.
4

Run and check the report

Run the job. It writes a new PST with only the unique emails, plus a CSV log of every group it kept or removed. Open the report in Excel to check the run.

Your original mailbox is never touched.

Your original mailbox is never touched

This is the part people worry about most, and the answer is simple. Your source file is left exactly as it was, byte for byte. Duplicates are never deleted in place. The unique messages are written into a separate new PST instead, and the mailbox you started with does not change at all. A wrong guess about what counts as a duplicate costs you nothing. You can try a more strict run whenever you like.

   
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Catches the duplicates Clean Up leaves behind

The Clean Up command built into Outlook only removes copies within a single conversation or folder. The real mess is spread wider. The same message sits in Inbox and in Archive, a whole account gets imported on top of another, threads multiply after a repair. One bad re-sync on a busy IMAP mailbox has been enough to push a 22,000-message folder past 33,000. The tool compares across every folder you check, so cross-folder copies finally get caught.

   
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Catches the duplicates Clean Up leaves behind.
Everything runs on your own PC.

Everything runs on your own PC

No upload, no web service, no cloud account. Everything happens on your own computer, and the clean copy is saved right there beside the original. For regulated inboxes in law or finance, that on-machine processing is a requirement rather than a bonus, and here it is the default.

   
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Match on the fields you choose

Six fields define a duplicate: Subject, sender, message body, recipients, date, and attachment names. Tick the ones that matter. The body is compared as a normalized hash, and RE: and FW: prefixes can be ignored so replies still line up.

You pick which copy survives

For every group of duplicates you choose the survivor. The default keeps whichever copy was found first, and one click switches that to the oldest or the newest. Useful when the tidier, better-filed copy of a thread is the one worth keeping.

Reads PST and OST directly

Both Outlook file types open the same way, with no Outlook profile or Exchange setup to configure. Browse the full tree, expand every level, and select only what you want scanned.

Filter before you clean

Narrow the message list with a text filter across the Subject, From, To, and body fields, then apply. It is easy way to preview a slice of the mailbox before committing to a full run.

A CSV report of every change

Each group is logged with its folder, Subject, sender, date, and whether the copy was kept or removed. The file is plain RFC4180 CSV with a UTF-8 marker, so it opens cleanly in Excel.

Optional backup of what was removed

Switch on the backup and the removed duplicates are saved to a second PST of their own. If you ever want them back, they are one import away.

Outlook Duplicate Remover
Outlook Duplicate RemoverOutlook PST Duplicate Remover Software cleans a whole PST in one pass. The original file stays exactly as it was.
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Who uses Outlook Duplicate Remover Software?

IT admins and migrators

Cleaning mailboxes after a PST import or an Exchange move, where the same messages routinely land twice and users start complaining about clutter.

Long-time Outlook users

A personal archive that grew across years and a couple of email accounts, now heavy and slow to open, full of copies nobody meant to keep.

Support and handover teams

Handed an inherited mailbox to slim down, such as an ex-colleague's 6 GB archive with three dozen subfolders, before it gets passed on to someone else.

Outlook Duplicate Remover
Outlook Duplicate Remover
Price
from $ 29.99
Version
1.6
File Size
8 Mb
Last updated on
23/08/26
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

Usually an IMAP account or importing the same PST twice. Syncing one mailbox on two machines will do it, and so will a rule that copies mail into a second folder, or a repair that re-downloads messages you already had. They pile up quiet until a folder is twice the size it should be.

Short answer: no. Long answer: Clean Up only clears redundant replies inside a single conversation or folder, so it misses the same email sitting in two different folders or brought in by a second account. That cross-folder case is exactly what Outlook Duplicate Remover handles.

Open the file straight in the app. It reads PST and OST on its own. You do not need Outlook, a mail profile or an Exchange account for any of it. You select the folders, set the match rules, and it writes a de-duplicated copy wherever you choose.

There are free scripts and VBA macros you can find online, but most of them delete messages straight out of your live mailbox, which is risky if the match is wrong. The trial here lets you to run on a sample first and see the results on a clean copy before you commit to the whole file.

No, never. The source PST or OST is only ever read, not written to. Every removal happens in a brand new file, and you can also keep a separate backup PST of the messages that were taken out, so nothing is truly gone.

Yes. Tick as many folders as you like and the comparison runs across all of them at once, catching copies that live in Inbox, Sent, and Archive at the same time. This is the gap in Outlook's native Clean Up that leaves most mailboxes cluttered.

You decide. By default the first copy found becomes the keeper, and you can switch that to the oldest or the newest in each group. Whatever you pick carries over into the clean PST as the original, and the rest are set aside.

Rate Outlook Duplicate Remover

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  • Windows 11
Author: SoftOrbits (English)
4.5
Avg. rating: 4.5 from 1140 votes
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Desktop software for Windows