I have had multiple copies of emails

Check the affected account in its own webmail first: if the duplicates appear there, this is a mailbox/service synchronization issue; if webmail contains one copy while Classic Outlook shows thousands, isolate and replace the affected Outlook profile.

Microsoft recorded a broad service incident around November 12, but its current Classic Outlook known-issues list does not identify the exact “messages repeatedly appear and disappear” symptom as a confirmed Classic Outlook defect.^1^ ^2^

1. Determine whether the duplicates exist in the mailbox

1. Close Classic Outlook so it cannot continue synchronizing.
2. Sign in through the affected email provider’s webmail—not BT Mail unless BT hosts that particular account.
3. Search for two or three messages that Outlook duplicated.
4. Check whether webmail shows:
   • One copy: the mailbox is intact; proceed to the Outlook profile steps below.
   • Multiple copies that also appear and disappear: the behavior is upstream of the local Outlook display. Leave Outlook closed temporarily and contact that account’s email provider or Microsoft support, as applicable.
5. Compare the unaffected account in its webmail as a control.

Do not bulk-delete the duplicates until this check is complete. If the copies are server-side, Outlook may synchronize those deletions across devices.

2. If webmail is correct, repair the affected account’s profile

In Classic Outlook:

1. Select File → Account Settings → Account Settings.
2. On the Email tab, select the affected account.
3. Select Repair, complete the wizard, and restart Outlook.^3^
4. Allow synchronization to finish, then check whether a single webmail message still appears multiple times.

The Repair option is unavailable for some account configurations. If it is absent or the problem continues, create a separate profile rather than removing accounts from the existing one:

1. Close Outlook.
2. Hold Shift while starting Outlook. Alternatively, press Windows+R, enter Outlook.exe /profiles, and press Enter.
3. Select Options → Prompt a profile to be used → New.
4. Give the profile a temporary name.
5. Add only the affected account initially.
6. Open that profile and let it synchronize completely.
7. If it remains stable, add the second account and retest.

This preserves the original profile while determining whether its settings or data files are responsible.^4^

3. If the new profile also duplicates messages

Test without Outlook add-ins:

1. Close Outlook.
2. Press Windows+R.
3. Enter outlook.exe /safe and select OK.
4. Test the affected account.

If the behavior stops in Safe Mode, go to File → Options → Add-ins, select COM Add-ins → Go, disable the add-ins, and then enable them individually until the responsible one is identified.^5^

POP account check

In File → Account Settings → Account Settings, inspect the account’s Type. Only follow this branch if it says POP/POP3.

POP downloads messages to local storage, and its server-retention setting affects whether another client can download the same messages. Review Change → More Settings → Advanced → Delivery and check other computers or mail applications accessing that same account.^6^

If it is IMAP, Outlook.com, or Exchange, do not look for Leave a copy of messages on the server; that option applies only to POP3.^7^

If duplicates remain in webmail after the November 12 incident is shown as resolved, provide support with the affected provider, account type, approximate start time, examples of duplicated message subjects/timestamps, and confirmation that only one of the two accounts is affected.

References

1. Microsoft service health status
2. Fixes or workarounds for recent issues in classic Outlook for Windows
3. Fix your Outlook email connection by repairing your profile
4. Create a profile in classic Outlook for Windows
5. [Classic Outlook](https://support.microsoft.com/outlook/getstarted/outlook-for-windows-not-responding-hangs-freezes-or-stops-working)
6. Read POP3 email messages on multiple computers
7. Leave a copy of the message on the server is missing in Outlook | Microsoft Support