If you use the POP3 protocol to configure your mailbox in Outlook, you may find that emails are deleted from your webmail inbox after they are downloaded. This is caused by a default setting in the Outlook client.
Go to Account Properties > Internet E-mail Settings > More Settings > Advanced. To prevent messages from being deleted from the server after they are downloaded to Outlook, make sure that the Leave a copy of messages on the server option is selected.
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