Why Copilot in Outlook Stops Mid-Reply When Drafting

Official documentation checked October 14, 2026.

If Outlook Copilot produces an incomplete reply, keep the compose window and preserve the text before retrying. Do not send a partial message to reset generation. The interruption alone does not prove a timeout, a policy block, or a particular thread-size limit.

Why Copilot Stops Generating Mid-Reply

An interrupted result can require investigation of the service, connection, account, client, source, or protection settings. Capture the actual error if one appears. The official drafting guidance does not establish a universal 30-second deadline, a 100-message thread limit, a 20 MB attachment cutoff, or an administrator control that raises an Outlook Copilot API timeout to 60 seconds.

Different Outlook features have different conditions. Microsoft documents Draft with Copilot controls for supported clients and notes that Draft with Copilot in new Outlook and the web does not support plain-text composition. The broader requirements also depend on the exact mailbox-grounded experience, license, and tenant configuration.

Steps to Resume Copilot After It Stops Mid-Reply

1. Preserve the incomplete draft

Keep the reply open and copy any useful unsaved text to an organization-approved temporary working location, or save it in the draft where possible. Record the error and time. Do not press an undocumented shortcut to “submit” the reply, and do not delete the unfinished sentence until you have preserved the text you need.

2. Use the supported regenerate or edit control

In the affected Copilot drafting experience, use the visible Regenerate or Regenerate draft control if offered, or edit the prompt and select Generate again. Microsoft describes these actions in the drafting guide; a universal Resume button is not documented.

Ask for a shorter, specific result, such as a brief reply covering the necessary points, and avoid unnecessary attachment or thread context. This is a practical way to simplify the request, not a verified timeout increase. If your client offers modification of selected text, use that control on the intended passage rather than replacing the entire preserved draft.

3. Review before keeping or sending

Compare the new output with the original messages. Check names, dates, commitments, recipients, tone, and any sensitive information. Accept the intended text using the client’s Keep, Keep it, or Insert action where available. Those actions and Send are separate steps. Send only after reviewing the complete draft.

4. Check the feature and protection conditions

If new Outlook or web composition is plain text, the documented HTML setting is Settings > Mail > Compose and reply. Use an HTML message where appropriate for the supported feature; do not alter organizational policy to force a protected workflow.

If a label or policy error is shown, have the administrator inspect the exact protection condition. Microsoft’s Copilot DLP guidance describes processing restrictions. A label’s name alone does not prove the cause, and removing encryption or requesting a blanket label exception is not a routine recovery step.

If Copilot Still Has Issues After the Main Fix

Try an approved non-sensitive sample draft with the same feature and compare a supported web client if available. If all attempts fail, ask the administrator to check service health, account conditions, and network requirements. Preserve the original draft rather than repeatedly pasting sensitive email content into another account or service.

If Copilot is missing altogether, follow Microsoft’s missing-button guidance and the applicable Outlook feature documentation. Do not enable an assumed Copilot COM add-in or search for an invented API timeout setting.

Copilot in Outlook: Draft Stop vs Timeout vs Policy Block

No Outlook reply or tenant configuration was tested for this review. The supported controls help preserve and retry a draft; they do not certify the cause or guarantee continuation from the exact stopped sentence.