How to Connect a Shared Mailbox, Microsoft Forms, and Attachments in Power Automate

This workflow is possible, but a single flow cannot pause indefinitely while an unknown user completes a form. Use two flows and a shared tracking key: the first stores the incoming attachment and sends the form link; the second starts when the form is submitted and retrieves the matching file.

Plan the Tracking Key and Storage Location

Create a SharePoint list with columns for Tracking ID, sender address, attachment path, status, and creation time. Store attachments in a controlled SharePoint document library rather than passing large binary content through a long-running flow.

Build the Two Power Automate Flows

1. Flow 1 uses When a new email arrives in a shared mailbox (V2). Enable attachment handling, generate a unique Tracking ID, save each attachment to SharePoint, and write its path to the tracking list.
2. Send the original sender an automatic reply containing the Microsoft Forms link and the Tracking ID they must enter in a required form field.
3. Flow 2 uses When a new response is submitted, followed by Get response details. Read the Tracking ID and find the matching SharePoint list item.
4. Use Get file content using path, then Send an email (V2) to the final recipient with the form answers and stored attachment. Mark the tracking record Complete.

Validate Missing or Duplicate Tracking IDs

Add a condition before retrieving the file. If no list item matches, notify the process owner instead of sending an incomplete email. If more than one item matches, stop and log the duplicate so the wrong attachment is never paired with a response.

Secure and Retain the Collected Files

Limit library access to the flow owners and intended reviewers, validate allowed file extensions, and add a retention or cleanup flow for completed records. Test with one small attachment before increasing connector limits or handling multiple files.

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Connect a Shared Mailbox, Microsoft Forms, and Attachments in Power Automate FAQs

Why are two flows better than one flow with a delay?

The Forms submission happens at an unknown time. A second trigger can start whenever the response arrives without keeping the mailbox flow running.

How does the second flow find the correct attachment?

Require the respondent to submit the Tracking ID sent by Flow 1, then query the SharePoint tracking list for that exact value.

Can the shared mailbox automatic reply include a prefilled Forms value?

Microsoft Forms prefilled-link options vary by form type. The safest design is to display the Tracking ID clearly and make it a required response field.

What happens if the incoming email has several attachments?

Store each file with the same Tracking ID and either attach all matching files in Flow 2 or create one child record per attachment.