'%3e%3cpath%20d='M8%200C12.4183%200%2016%203.58172%2016%208C16%2012.4183%2012.4183%2016%208%2016C3.58172%2016%200%2012.4183%200%208C0%203.58172%203.58172%200%208%200ZM11.6162%204.38379C11.2257%203.99337%2010.5927%203.99338%2010.2021%204.38379L8%206.58594L5.79785%204.38379C5.40732%203.99334%204.77429%203.99329%204.38379%204.38379C3.99331%204.77429%203.99335%205.40733%204.38379%205.79785L6.58594%208L4.38379%2010.2021C3.99348%2010.5927%203.99341%2011.2257%204.38379%2011.6162C4.77426%2012.0066%205.40734%2012.0065%205.79785%2011.6162L8%209.41406L10.2021%2011.6162C10.5927%2012.0066%2011.2257%2012.0067%2011.6162%2011.6162C12.0067%2011.2257%2012.0066%2010.5927%2011.6162%2010.2021L9.41406%208L11.6162%205.79785C12.0066%205.40735%2012.0066%204.77429%2011.6162%204.38379Z'%20fill='%23080E17'%20fill-opacity='0.46'/%3e%3c/g%3e%3cdefs%3e%3cclipPath%20id='clip0_3761_713'%3e%3crect%20width='16'%20height='16'%20fill='white'/%3e%3c/clipPath%3e%3c/defs%3e%3c/svg%3e)
Fix Shared Mailbox Automatically Resending Old Emails in Outlook
Question details
Investigate and resolve an issue where a role-based or shared mailbox is unexpectedly resending old emails without them appearing in the Outbox.
- Product
- Microsoft Outlook
- Device & OS
- not provided
- Scenario
- A shared mailbox is sending out duplicate or old emails automatically, causing confusion, and these emails cannot be found in the local Outbox before sending.
- Observed behavior
- Old messages are automatically resent from the shared mailbox to recipients, bypassing the Outbox and operating independently of active user input.
Verify with other team members who have delegate access to the shared mailbox to ensure no one is manually resending these messages, and temporarily disable any third-party Outlook add-ins or CRM integrations.
Run a Message Trace in Exchange Admin Center
Use the Exchange admin center to identify the exact origin, sender IP, and delivery path of the unexpectedly resent messages.
A message trace is the most effective way to determine how and why an email was sent from a shared mailbox. It bypasses local client issues and shows the server-side reality of the message flow.
Go to the Microsoft 365 admin portal and navigate to the Exchange admin center using your administrator credentials.
In the left-hand navigation pane, click on 'Mail flow' and then select 'Message trace'.
Click 'Start a trace'. Enter the shared mailbox address in the 'Senders' field and adjust the time range to cover the period when the old emails were resent.
Run the report and click on the specific sent emails. Look at the 'Message events' and 'Client IP' to determine if it was triggered by a specific user, an automated organization policy, or a third-party application.
Review Mailbox Audit Logs
Check the audit logs to see if another user with permissions is accessing the mailbox and performing 'Send As' actions.
Run Microsoft Support and Recovery Assistant (SaRA)
Use the automated tool provided by Microsoft to diagnose and fix configuration or synchronization issues in Outlook.
Boost Productivity with a Free Microsoft Office Alternative
Troubleshooting Exchange Server issues can be complex and usually requires IT admin tools. While fixing server-side mailbox routing involves Microsoft configurations, handling your daily documents, spreadsheets, and presentations shouldn't be stressful. WPS Office offers a free, lightweight, and highly compatible alternative to Microsoft Office.
- 1. Visit the Official Website: Go to the official WPS Office website to access the latest free download.
- 2. Download the Installer: Click the 'Free Download' button to get the installation file for your operating system.
- 3. Install and Start Creating: Run the installer, follow the simple setup steps, and start enjoying a seamless office alternative instantly.
Frequently Asked Questions
Can organizational retention policies cause old emails to resend?
Yes. In some instances, automated policies designed to delete or archive old emails can interact with server rules or third-party add-ins, triggering sync errors or automated alerts that mimic the behavior of resending old emails.
Why didn't the resent emails appear in the Outlook Outbox?
If emails are sent directly by the Exchange Server (due to a rule, a policy, or a corrupted server-side sync state) or via an API by a third-party application, they bypass the local Outlook client entirely, meaning they will never show up in your local Outbox.
Can a third-party app or add-in cause this issue?
Yes. CRM integrations, antivirus scanners, or email tracking add-ins that have access to the shared mailbox can sometimes get stuck in a loop or process old queued messages erroneously, causing them to be sent out again.
How can I check who sent an email from a shared mailbox?
Administrators can run a Message Trace in the Exchange admin center or review Mailbox Audit Logs in the Microsoft Purview compliance portal. This will reveal the client IP address and the specific user account that performed the 'Send As' action.
