How to Fix Duplicate Emails in Your Outlook Sent Folder With IMAP

You send one email, but two copies appear in your Sent folder. Over time this wastes space, makes searching messy, and leaves you wondering if the other person also received the message twice. If you use Outlook with an IMAP account, this is a very common problem with a clear cause.

The good news is that the recipient usually receives only one copy. The duplication happens on your side, when both Outlook and your mail server save their own copy of the same sent message. This guide explains why it happens and shows you how to stop it in both classic Outlook for Windows and the newer versions.

Quick Answer

Turn off Outlook’s option to save sent messages, or set Outlook not to save a copy when the server already does. In Outlook, go to File, Options, Mail, and untick Save copies of messages in the Sent Items folder, or in Account Settings set the account to Do not save copies of sent items. Your server will still keep one copy in the Sent folder, so you will see just one.

Why Duplicate Emails Appear in the Sent Folder With IMAP

IMAP keeps your mail on the server and syncs it to your devices. When you send a message, two systems may try to save it at the same time.

First, Outlook saves a local copy in Sent Items because its save setting is turned on. Second, your email provider’s server also saves a copy automatically when it sends the message. When Outlook next syncs with the server, it downloads the server copy as well. Now you have two identical messages sitting side by side.

This is different from POP3, which worked mostly on one computer. With IMAP, saving is shared work, so you need to let only one side do the job. Most modern providers, including Gmail, Outlook.com, Yahoo, and many business hosts, save sent mail on the server by default. That is why the fix is usually to stop Outlook from saving its second copy.

Duplicates can also happen after you change providers, import old mail, or set up the same account twice in Outlook. Those cases need slightly different checks, which are covered below.

Before You Change Settings

• Confirm the recipient got only one copy by asking them or testing with your own second address.
• Check whether duplicates appear on webmail too. Log in to your provider’s website and look at the Sent folder there.
• Note which Outlook you use: classic Outlook for Windows, new Outlook, or Outlook for Mac. Menu names differ a little.

If duplicates appear only in Outlook and not on webmail, the saving conflict described above is almost certainly the cause. If they appear on webmail too, your provider or a phone app may also be saving extra copies, and you will need to check that device as well.

Fix Duplicate Sent Emails in Classic Outlook for Windows

Method 1: Change the Account Setting

1. Open Outlook and click File, then Account Settings, then Account Settings again.
2. Select your IMAP account and click Change.
3. Click More Settings and open the Advanced or Sent Items tab, depending on your version.
4. Choose the option Do not save copies of sent items.
5. Click OK, Next, and Finish, then restart Outlook.
6. Send a test email and wait a minute for syncing. Check the Sent folder. Only one copy should appear.

Method 2: Turn Off the Global Save Option

1. Click File, then Options, then Mail.
2. Scroll to the Save messages section.
3. Untick Automatically save a copy of sent messages or Save copies of messages in the Sent Items folder.
4. Click OK.

Use one method, not both blindly if you have more than one account. The account-level setting is better when you have mixed accounts, for example one IMAP account and one work account that behaves differently. The global option affects all accounts in that Outlook profile.

Microsoft explains these options in its official guidance on changing where sent email messages are saved in Outlook. If your menus look slightly different, that page shows the current layout for supported versions.

Fix Duplicates in New Outlook and Outlook for Mac

The new Outlook for Windows and Outlook for Mac rely more heavily on server settings. There may not be the same More Settings window.

1. Open Settings from the gear icon.
2. Go to Mail, then Compose and reply or Message handling, depending on your version.
3. Look for an option about saving sent items and make sure Outlook is not saving an extra copy when the provider already does.
4. If there is no such option, remove and re-add the account using the automatic setup so Outlook picks up the provider’s correct Sent folder mapping.

On Mac, also check Mailbox Behaviours in the account settings inside Outlook Preferences. Make sure the Sent mailbox points to the server’s Sent folder, not to a local On My Computer folder, which can cause sync confusion.

Check That Outlook Uses the Correct Sent Folder

Sometimes Outlook and the server use different folders, such as Sent, Sent Items, and Sent Mail. That mismatch can look like duplication or missing sent mail.

1. Right-click your account name in the folder pane and choose IMAP Folders if available.
2. Click Query and review which folders are subscribed.
3. Make sure only the correct Sent folder is in use and subscribed.
4. On webmail, confirm the folder the provider uses for sent mail has the same name.

Do not delete extra Sent folders until you have checked they are empty and your real sent mail is safe in the correct folder. Move anything important first.

If you recently moved accounts, you may also find our guide on how to switch an Outlook account from POP3 to IMAP without losing emails helpful, because old POP3 sent folders often sit alongside new IMAP folders and cause confusion.

Remove Existing Duplicate Copies Safely

Fixing the setting stops new duplicates, but it does not remove the ones already there.

1. Sort the Sent folder by date and subject so duplicates sit together.
2. Select one copy of each pair, check it is truly identical, and delete it.
3. For a large folder, work in small batches and empty the Deleted Items folder only when you are sure.

Outlook does not have a powerful built-in duplicate remover for sent mail. Be careful with third-party cleanup tools. Always back up your mailbox or export the Sent folder before running any bulk cleanup, so you can recover if the tool removes too much.

What If Duplicates Still Appear?

If you still see two copies after changing settings, work through these checks:

• Same account added twice: Go to Account Settings and make sure the account is listed only once.
• Phone or tablet also saving copies: Some mobile apps have their own save-sent setting. Turn it off on one device only.
• Rules or add-ins: Disable add-ins temporarily and check if any rule copies sent mail to another folder that syncs back.
• Gmail accounts: Gmail always saves sent mail itself. For Gmail IMAP in Outlook, the do-not-save setting is especially important.

Send several test messages after each change, one at a time. Changing three things at once makes it hard to know which fix worked.

Common Mistakes to Avoid

• Deleting the server Sent folder: This can delete sent mail on all devices because IMAP syncs deletions everywhere.
• Turning off saving everywhere without testing: If your provider does not save sent mail on the server, you could be left with no copy at all. Always send a test and confirm one copy remains on webmail.
• Assuming the recipient got two emails: In most cases they did not. Check before apologising or resending.
• Cleaning duplicates without a backup: Bulk deletion is risky. Export first.
• Ignoring folder mapping: Changing the save setting alone will not help if Outlook is watching the wrong Sent folder.

Conclusion

Duplicate emails in the Outlook Sent folder with IMAP almost always mean both Outlook and your mail server are saving a copy of the same message. Let the server do the saving, turn off Outlook’s extra copy in the account settings, and confirm the correct Sent folder is selected. Test with a new message, then clean up old duplicates carefully. After that, your Sent folder should show exactly one copy for every email you send.

Frequently Asked Questions

Does the other person receive my email twice when I see duplicates?

Usually no. The duplication happens when the sent message is saved, after it has been delivered once. If you are worried, test by sending to your own second address and count how many arrive in the inbox.

If I turn off saving in Outlook, will I lose my sent emails?

No, as long as your provider saves sent mail on the server, which most IMAP providers do. After changing the setting, send a test and check webmail. You should still see one copy in the Sent folder there and in Outlook.

Why did duplicates start after I changed my phone?

A new phone app may have started saving its own sent copy, or it may have added the account with different folder settings. Check the app’s sent-mail setting and compare the Sent folder name with what Outlook uses.

Can I automatically delete all old duplicates at once?

Outlook does not offer a safe one-click duplicate remover for the Sent folder. Sorting and deleting in small batches is safest. If you use a third-party tool, export a backup first so you can undo mistakes.

Is this problem specific to IMAP?

It is most common with IMAP because saving happens on both the app and the server. POP3 accounts work differently and are less likely to have this exact sync conflict, though they can have other duplication issues.