Practical troubleshooting guide · The business scenario is illustrative, not a client case study. Administrative changes require authorised access.

An accounting or consulting office in St. Catharines uses an enquiries mailbox. One person answers a request, but another cannot find the reply and sends a second response. Before assuming Outlook lost the email, check where delegated sent messages are being saved and whether everyone is opening the same mailbox.

Establish which identity sent the reply

Open a harmless test message and inspect its From address. A reply from a personal account is different from Send As or Send on Behalf of the shared mailbox. Check the sender’s own Sent Items as well as the shared folder. Confirm the test account already has the intended permissions; sent-copy settings do not grant permission to read or send.

Configure shared copies

Microsoft 365 has shared-mailbox Sent items settings for copying messages sent as the mailbox and messages sent on its behalf. An authorised administrator can enable the appropriate options in the shared mailbox settings. Choose the options that match the team’s workflow and record the previous values. This addresses future copies; do not promise it will recreate missing historical conversations.

Test both visibility and behaviour

Send a new labelled message from the shared address and have a second authorised user find its copy in the shared Sent Items. Test the client your team actually uses and compare Outlook on the web if a desktop view appears stale. Verify the recipient sees the expected sender identity. Avoid sharing the mailbox password to work around a permissions or synchronisation problem.

Add ownership to the conversation

A visible sent copy helps with handover but does not assign a request or prevent two people answering at once. Agree how staff indicate that an enquiry is being handled and when it is complete. Start with a small shared routine before buying another system. If the volume needs formal assignment and tracking, discuss whether a ticketing tool better fits that workload.

MAKE IT ACTIONABLE

Your next steps

  • Check the sender identity and both Sent Items folders.
  • Enable the appropriate shared-copy options.
  • Test from two separately authorised accounts.

Official reference

Microsoft: Configure shared mailbox settings

Technical guidance checked October 1, 2026. Product features and requirements can change. The business checklists above are practical suggestions from Cyber Bounds.

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