Duplicate e-mails in Outlook: where they come from and how to stop them

E-mail·· 5 views· 3 min read

The short answer: duplicate e-mails in Outlook are almost never the sender sending twice. They come from the same account set up twice, a POP account downloading what it already had, a rule that copies instead of moving, or a forwarder that brings mail back into the same mailbox.

Where they come from

Symptom Most likely cause
Every e-mail appears twice, always The account was added twice to the same Outlook profile (sometimes once as IMAP and once as POP).
All the old ones come back at once A POP account lost track of what it had downloaded and downloads everything again. Or the data file was rebuilt.
Only mail going into one folder doubles An Outlook rule with “copy to” instead of “move to”, or two rules doing the same.
Only mail from one address doubles A forwarder or a distribution list that includes your own mailbox.
Only sent mail appears twice Outlook keeps a copy and the server keeps another. See sent and deleted items with IMAP.

Stopping the duplicates

1 Count the accounts: in File > Account Settings, check whether the same address appears more than once. If so, remove the extra account (check first whether it is POP: POP or IMAP).
2 Review the rules: File > Manage Rules & Alerts. Look for repeated rules or ones that “copy”. Switch them off one at a time to find the culprit.
3 Check forwarders in cPanel: under Forwarders, make sure no address forwards to the mailbox itself or to another one you also have in Outlook.
4 Compare with webmail: if there are no duplicates there, Outlook is creating them. If there are, the server receives twice (forwarder or list).
5 To clean the ones already there, sort the folder by date received and delete repeats in blocks, or use Outlook’s conversation clean-up.
Before removing a POP account, make sure the mail exists somewhere else. If the POP account is the only one with the history, removing it can delete messages that exist only on that computer.
Moving to IMAP ends most duplicates for good: there is a single copy, on the server, and every device shows the same one.

Duplicates still coming? Tell us the address and whether you see them in webmail too.

Open a support ticket

SEE ALSO

POP or IMAP: which to choose, and what you lose by picking wrong

Sent and deleted e-mails missing in Outlook with IMAP: setting the right folders

Outlook is not syncing: missing e-mails and folders that do not update

How to stop spam in Outlook: the filter on your computer and the one on the server

How to access your webmail

Webmail or an e-mail app: which one to read your mail with

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