Urgent Email Migration Playbook: What UK IT Teams Must Do Now if Gmail Changes Break Your Flow

Your urgent problem: Gmail changes just hit — and you need to move fast

If Google’s 2025–26 Gmail changes (AI features and new account routing options) have introduced unexpected risks — data residency concerns, automated AI access to mail or an organisational policy decision to exit Google Workspace — this runbook gives UK IT teams a rapid, repeatable pathway to move users off Gmail or implement a safe dual delivery pause without breaking business email flow.

Why this matters now (UK 2026 context)

Late 2025 and early 2026 saw major product policy shifts from large cloud providers and renewed regulatory scrutiny in the UK around AI and data transfers. The Information Commissioner’s Office (ICO) and UK GDPR interpretations are increasingly focused on who (or what) has access to personal data — and email is one of the most sensitive sources. If your legal, security or procurement teams are pushing for a migration, you need an operational plan that is fast, reversible and compliant.

Quick truth: you can’t wait weeks to respond. Email is mission-critical — a controlled, staged migration or temporary dual delivery is the safest way to protect business continuity while you address compliance and technical concerns.

Inverted-pyramid summary: top actions in the first 48–72 hours

1. Inventory & risk triage — list affected domains, number of mailboxes, privileged accounts, and regulatory flags.
2. Enable emergency dual delivery to mirror inbound mail to a secondary MX/archival endpoint while keeping Gmail in place.
3. Lower DNS TTL (to 300s) now to prepare for an MX cutover.
4. Export and archive high-risk mailboxes (legal, HR, finance) to secure storage or vault.
5. Legal check — confirm DPAs, data residency, and update DPIA / transfer risk log.
6. Plan a pilot of 10–50 users within 72 hours and run deliverability tests.

Step-by-step emergency runbook (detailed)

Phase 1 — Rapid discovery (0–8 hours)

• Inventory: export a CSV of all domains, users, aliases, groups, shared mailboxes and service accounts from Google Workspace Admin. Prioritise by business-criticality and compliance category (e.g., HR, Finance, Legal = high).
• Document dependencies: mail-based integrations (ticketing, CI/CD alerts, CRM), email-to-case flows and service accounts that send/receive email.
• Identify mail routing owners: DNS, security, legal, and app owners for a fast approval path.

Phase 2 — Containment: Dual delivery & mirroring (8–24 hours)

Dual delivery buys time. The aim is to ensure inbound mail continues to be delivered to Gmail while copies are routed to a secondary system for inspection, archival and staged migration.

1. Choose the secondary endpoint: an on-prem MTA, a cloud mail host, or an archival/journaling mailbox that supports SMTP intake.
2. In Google Workspace Admin Console, configure routing: create a custom inbound routing rule to deliver a copy to an external SMTP server (or set up journaling). Document the external server hostname and credentials.
3. Enable TLS and authentication between Google and your external endpoint. If your external endpoint uses IP allowlisting, add Google’s outbound mail IPs per Google documentation.
4. Validate delivery by sending test messages and verifying identical copies arrive at both Gmail inbox and the secondary endpoint.

Why this matters: dual delivery prevents data loss, gives compliance teams a read-only record and reduces pressure to cut MX records immediately.

Phase 3 — Backup & legal preservation (24–48 hours)

• Export high-risk mailboxes: use Google Vault exports or third-party tools. For fast exports, use Google Takeout only for individual high-risk accounts, and Vault for legal holds.
• Perform DPIA / legal sign-off: update your DPIA for the migration, record the lawful basis for processing, and confirm data transfer mechanisms if the new provider stores data outside the UK.
• Preserve logs: export admin audit logs, message logs and any access reports needed for potential investigations.

Phase 4 — Pilot migration (48–72 hours)

Run one or more pilots to validate the full migration steps: mailbox data migration, calendar and contact transfer, and end-user authentication to the new provider.

1. Select pilot users: include a senior sponsor, a helpdesk user and 5–10 regular users from different teams.
2. Migrate mail: use imapsync for a fast IMAP-level copy or a vendor migration tool for larger, mailbox-level metadata fidelity. Example imapsync command (replace credentials and hosts):

   imapsync --host1 imap.gmail.com --ssl1 --user1 alice@yourdomain.com --password1 'GMAIL-PASSWORD' --host2 imap.newmail.example --ssl2 --user2 alice@yourdomain.com --password2 'NEW-PASS'

3. Test calendar & contacts: confirm calendar invites, recurring meetings and shared calendars render correctly. If using Exchange/365, migrate calendars with native tools or 3rd-party connectors.
4. SSO & MFA: configure SSO with your identity provider (Okta, Azure AD, or SAML IdP) and enforce MFA for pilot users. Validate login flows and token lifetimes.

Phase 5 — DNS & MX cutover checklist (the critical minutes)

DNS cutover is the riskiest operational step. Prepare and execute with a tightly controlled checklist.

1. Pre-cutover (48–72 hours):
   • Set domain TTLs for MX records to a low value (300 seconds) — change this at your DNS provider for both primary domain and any subdomains used for mail.
   • Prepare the exact MX records provided by the destination provider and verify via their admin console.
   • Update SPF records to include the new provider; plan to keep both Google and new provider in the SPF include list during transition.
   • Generate DKIM keys on the new provider and prepare TXT records for publishing.
   • Document rollback MX entries (original Google MX values) and who is authorised to execute rollback.
2. Cutover window:
   • Announce the precise 30–60 minute maintenance window to stakeholders and support teams.
   • At T-15 minutes, clear queue/backlog on current mail servers and suspend non-essential mail processing tasks.
   • Change MX records to the new provider’s MX hostnames at your registrar/DNS provider.
   • Immediately monitor MX propagation (use dig MX yourdomain +short and online DNS propagation tools). Expect SMTP to start flowing to the new MX within TTL bounds.
3. Post-cutover (0–24 hours):
   • Monitor inbound delivery rates, NDRs and bounce patterns.
   • Update SPF to remove Google includes only after you are confident no legitimate mail will be sent from Google (or keep for long tail for 7–14 days).
   • Publish new DKIM selectors and rotate if needed; adjust DMARC policy incrementally from p=none → p=quarantine → p=reject over days to weeks.

Rapid validation tests (immediately after cutover)

• Send test messages from public providers (Gmail, Outlook.com) and internal services to confirm inbound delivery.
• Verify outbound mail IPs are included in SPF and reverse DNS matches expected HELO/EHLO names.
• Confirm mail flow for integrations (ticketing, alerts) both inbound and outbound.
• Run mailbox sampling: open migrated mailboxes to verify recent mail, labels and folder structure.

Legal and compliance run-list for UK IT teams

Always align migration with records and legal obligations. Here's a concise checklist:

• Update DPA and vendor assessments: ensure the new provider’s DPA meets UK GDPR obligations; retain evidence of security controls.
• Data residency: confirm where mail and attachments will be stored and cross-check with contracts and policy (sensitive HR/health/finance data may require local storage or specific safeguards).
• DPIA: update or create a DPIA covering the migration, AI access to mail content and any processing by downstream systems.
• Retention & eDiscovery: map retention holds and ensure the new provider supports equivalent or better legal hold features.
• Transfer mechanisms: for transfers out of the UK, confirm adequacy decisions or use SCCs/UK Addendum mechanisms where required.

Rollback & contingency planning

Every cutover must include a clear rollback plan. Keep these items ready:

• Original Google MX records and DNS admin credentials.
• Scripts or a documented sequence to update MX/SPF/DKIM quickly.
• Communication template for stakeholders and users announcing rollback and expected impact.
• Decision gates tied to specific KPIs (e.g., >2% NDRs in 60 minutes or critical app failures).

Migration timelines — examples

Small organisation (50–250 users)

1. Day 0 — Discovery & dual delivery setup.
2. Day 1 — Export of executive and legal mailboxes, pilot with 10 users.
3. Day 2–3 — Full migration by batch (50–100 mailboxes/day) with DNS cutover on Day 2.
4. Days 4–14 — Post-migration validation and SPF/DKIM/DMARC hardening.

Enterprise (1,000–10,000+ users)

1. Week 0 — Full discovery, legal sign-off and pilot design.
2. Week 1 — Dual delivery & pilot; migrate 50–200 pilot users.
3. Week 2–6 — Staged batches by business unit; cutover domains per region; longer co-existence windows (30–90 days) for compliance.
4. Week 6–12 — Archive consolidation, decommission Gmail and update retention policies.

Tools, vendors and tactical tips (2026 updates)

In 2026 there is a stronger market for specialist migration vendors that can handle metadata, labels and shared resources reliably. Consider vendors that provide:

• End-to-end migration with calendar and shared drive fidelity.
• Built-in journaling for legal hold and archiving during transition.
• Capabilities to preserve labels and message metadata (read status, flags).

Common tools and quick mentions:

• imapsync: fast, scriptable IMAP transfers for emergency migrations; see large-transfer playbooks like FilesDrive for handling bulk exports.
• Commercial migration tools (evaluate on UK data residency and support for retention/labels).
• DNS & monitoring tools (for fast MX changes and propagation checks).

Deliverability and anti-abuse considerations

• Update SPF immediately to include the new provider. During transition, list both providers to avoid legitimate outbound failing SPF checks.
• Rotate DKIM keys when you switch providers; publish new selectors in DNS before full cutover where possible.
• Monitor DMARC reports to catch spoofing or misconfiguration quickly.

Communication: stakeholder & user templates

Clear communication minimises helpdesk load. Use concise, time-boxed notices and post-migration guidance.

Sample status notice (short):

We are implementing an urgent email resilience change due to recent product policy updates. Expected impact: none for most users. If you have issues sending/receiving mail, contact IT support at it-support@yourorg.example. Planned window: 09:00–10:00 on DATE.

2026 trends & future predictions — what IT leaders should plan for

• AI access governance: expect stricter rules about LLM/AI access to hosted email data. Contractually insist on explicit controls and audit logs; see edge LLMs and governance notes.
• Localized hosting demand: more UK and EU-based secure email providers will emerge to meet data residency demands; budget for slightly higher OPEX if you need onshore hosting.
• Shift to Zero Trust and identity-first email: integrations with ZTNA/conditional access will be a purchasing criterion.
• Vendor lock-in scrutiny: procurement teams will demand migration and egress guarantees; include exit terms and data export commitments in contracts. See thoughts on rebuilding trust and transparency.

Actionable takeaways — what to do in the next 24 hours

1. Create the inventory CSV and classify 10 high-risk mailboxes for immediate export.
2. Enable dual delivery/journaling in Google Workspace to a secure endpoint and validate with test messages.
3. Lower your MX TTL to 300 seconds to prepare for a fast cutover if needed.
4. Call legal/compliance and confirm any international transfer impacts with the new provider.
5. Plan a 48–72 hour pilot for 10–50 users and schedule a clear cutover window with rollback gates.

Final checklist before you act

• Inventory complete and owners identified
• Dual delivery validated
• Backups and Vault exports secured
• DNS TTL reduced and MX values prepared
• Legal sign-off and DPIA updated
• Pilot scheduled with support teams on standby

Closing — why decisive action protects your business

In 2026 the balance between innovation and data control is shifting. For UK organisations, the right migration strategy protects regulatory posture, preserves business continuity and avoids downstream surprises from AI-enabled services. Use this runbook to stabilise mail flow now, buy time with dual delivery, and migrate on your schedule with full compliance visibility.

Need expert help?

If you want a tailored migration plan or emergency hands-on support to deploy dual delivery, validate your DNS cutover, or complete a pilot in 48 hours, contact us. Our team specialises in UK-compliant email migrations and can provide runbook automation, compliance documentation and on-call support to minimise risk.

Call to action: Start the migration readiness assessment now — request an emergency audit and pilot plan from our team to protect your organisation from unintended Gmail policy impacts.

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