Email Cutover Rollback — runbook

2026-06-06 status: The original cutover runbook (built around the use_workspace_email feature flag from #1438) is archived at docs/archive/runbooks/email-cutover-rollback-pre-1722.md.

The Gmail-API-polling inbound path shipped via PR #1722 (commit d8333558, 2026-06-05). The Cloudflare Worker is now a fallback during a 2-week production soak; #1441 tracks its final decommission.

For the current email-channel architecture (Gmail API polling + DWD impersonation outbound), see:

• docs/features/channels.md §System 4 (Email)
• docs/decisions/030-channel-credential-isolation.md
• docs/ops/EMAIL-CHANNEL-SETUP.md

If you actually need a rollback procedure for the Gmail-DWD path today, file a doc-gap issue: there isn't one yet, because the production cutover is the soak window, not a flag flip. The CF Worker remains the rollback target until #1441 closes.