Stop duplicate emails in Outlook by fixing the source first. Tick one account setting on IMAP accounts because the server and Outlook both save sent mail. Tick Do not import duplicates during every PST import. Both settings stop new copies and delete none that exist. Duplicate remover software finds the old copies in many folders. Scan a copy of the PST file and make a backup before you delete anything.
Sent Items shows every message twice or a PST import adds the same mail again. New copies keep arriving and manual deleting never ends.
This guide explains how to stop duplicate emails in Outlook and how to remove the copies you already have.
Why do Duplicate Emails Keep Coming Back?
Two sources create most copies:
- IMAP Sent Mail. On an IMAP account the server stores a sent message and Outlook uploads the same message again according to Microsoft.
- Repeated Imports. Importing a PST file adds a second copy of any message the folder already has.
Settings affect new mail only. Copies already in a folder remain there until you delete them.
Which Fix Matches Your Copies?
Match your case in the table:
| Your Case | Best Step | Method |
|---|---|---|
| Every sent message shows twice | IMAP setting | Method #1 |
| Copies appear after a PST import | Import option | Method #2 |
| Copies already fill many folders | Remover software | Method #3 |
3 Ways to Stop Duplicate Emails in Outlook
Methods 1 and 2 stop new copies for free. Method 3 removes copies that exist:
| Method | Effect | Cost |
|---|---|---|
| IMAP Setting | Stops sent mail copies | Free |
| Import Option | Stops import copies | Free |
| Remover Software | Deletes existing copies | Paid |
Method #1: Stop Sent Items Copies on an IMAP Account (Free)
Microsoft explains the problem in its article on duplicated IMAP sent messages. Four steps apply the setting in classic Outlook:
- In classic Outlook click File and then Account Settings.
- Choose Account Settings from the menu.
- Double click the IMAP account.
- Tick Don't save copies of sent items and click Next then Done.
Note: Microsoft calls this a workaround and says it does not always fix the problem. Bcc recipients can disappear from Sent Items with some providers.
Method #2: Stop Import Copies by Excluding Duplicates (Free)
Outlook skips messages that the destination folder already has when you tick the option. Seven steps set it:
- Back up the Outlook data file first.
- Open the File tab then choose Open & Export and Import/Export.
- Choose Import from another program or file. Click Next.
- Choose Outlook Data File (.pst) and continue with Next.
- Use Browse to find the PST file.
- Tick Do not import duplicates and move on with Next.
- Choose the destination folder and click Finish.
Note: Tick the option before every merge of another PST file into your mailbox.
Method #3: Remove the Existing Copies With EmailDoctor Outlook Duplicates Remover (Software)
Settings never remove copies that already exist. Outlook has no built in tool for exact copies across folders.
EmailDoctor Outlook Duplicates Remover software finds copies in many folders and PST files. Outlook does not need to be installed.
Add the File and Choose the Scope
Three steps prepare the scan:
- Use Add File(s) for the PST copy or Add Folder or Search Files for many files.
- Choose Across Folder(s) to compare one folder with another or Within Folder(s) to compare inside single folders. Click Next.
- Tick the folders on the Select tab. Click Change and set the Destination.
Set the Rules and Process the Copies
Three steps finish the work:
- Tick Email in the Filter tab.
- Open Specify Duplicate Criteria, tick the fields that must match and click Save.
- Select the action for the copies. Click Next and OK.
Note: EmailDoctor names no demo limit. Test one copied folder before buying a license.
How to Read Your Result
Check the mailbox after every fix:
| Result | Meaning | Next Step |
|---|---|---|
| Sent mail shows once | IMAP setting worked | Delete old copies with Method #3 |
| Copies still arrive after an import | Option was off | Tick it before the next import |
| Copies sit in many folders | Settings cannot reach them | Use Method #3 |
| Folder shows fewer items | Remover worked | Check Deleted Items |
Frequently Asked Questions
How do You Prevent Duplicate Emails Permanently?
Fix the source. Tick Don't save copies of sent items on IMAP accounts and Do not import duplicates during every import.
Why is Sent Mail Duplicated in Outlook?
On an IMAP account Microsoft says both the server and Outlook save the sent message.
Do the Settings Delete Copies That Already Exist?
No. Settings stop new copies only. Use remover software for the old ones.
Does Duplicates Remover Software Need Outlook?
No. Outlook does not need to be installed on the computer.
Where do Removed Copies Go?
You choose the action for the copies in the last step. Test one folder first.
Author’s Verdict
Fix the source first. Both settings stop new copies at no cost.
Use remover software when copies sit in many folders. Scan a copy of the PST file only.
- IMAP accounts save sent mail twice unless you tick one setting.
- Tick the import option that excludes duplicates.
- Settings never delete old copies.
- Remover software finds exact copies across folders.
Next Read: Remove Duplicate Emails From Outlook
Also Read: Why Outlook is Downloading Duplicate Emails | Clean Up Outlook Mailbox
