It could take place on any sent or received email items. multiple or duplicate email copies are a result of corruption. Below listed are the top reasons that are explained one by one. There are multiple reasons behind duplicate emails that might be sent or received in Outlook. Top 6 Reasons Why Duplicate Emails Problem Occur in MS Outlook To help you understand the duplicate emails problem, we have explored all the top possible reasons and apt solution that will surely help you to remove duplicate email items. Try automated tool Kernel for Outlook Duplicates Remover to detect & find duplicates MS Outlook items.