TL;DR
- DNS misconfiguration is the #1 cause of email migration failure — wrong MX order or missing SPF merge.
- 5 common mistakes: DNS errors, forgotten local data, no inventory, calendar loss, cutting over too fast.
- Follow 3 phases: Prepare (inventory, backup, lower TTL), Migrate (sync, DNS in order), Post-migration (keep old system, monitor).
- Key rule: keep both systems running for at least 72 hours after cutover.
Description
A complete guide to migrating business email. Covers 5 common mistakes, a 3-phase migration checklist, DNS order, post-migration stabilization, and tool recommendations.
Why Email Migration Is a Business Risk
You're switching providers — one of the riskiest IT operations for a small business. Most treat it as a technical task. Then emails stop flowing, calendars vanish, and CRM breaks.
The #1 cause: DNS misconfiguration. Wrong MX order, missed SPF merge, skipped DKIM — these cause bounces and spam for days. The fix is a proven checklist.
The 5 Most Common Mistakes
1. DNS errors. Changing MX too early causes split delivery. Not lowering TTL means slow propagation. Multiple SPF records break authentication.
2. Local data lost. PST, MBOX, POP3 messages — none transfer automatically. Also: server-side rules, signatures, templates.
3. No inventory. Missed aliases, shared mailboxes, distribution lists, catch-all addresses, non-human accounts.
4. Calendar/contact gaps. Email tools move messages, not events, contacts, or permissions. These need separate export.
5. Cutting over too fast. Keep both systems running 72 hours minimum (7-30 days ideal).
The Migration Checklist
Phase 1: Prepare (Days 1-10)
- Inventory all mailboxes, aliases, distribution lists, catch-all, non-human accounts
- Document DNS: MX, SPF, DKIM, DMARC. Screenshot for rollback
- Back up all mailboxes to PST/MBOX (1-4 hours per GB)
- Lower DNS TTL to 300 seconds, 24-72 hours before cutover
- Build all mailboxes on destination before changing DNS
- Notify team: timeline and required actions
Phase 2: Migrate (Cutover Day)
- Run initial IMAP sync. Start days ahead for large mailboxes
- Export/import contacts and calendars separately
- Recreate rules, signatures, permissions manually
- Update DNS in order: MX → SPF (merge into ONE record) → DKIM → DMARC (p=none)
- Run delta sync; validate inbound/outbound/aliases/mobile
- If validation fails: restore old DNS, keep old provider, retry after 24h
Phase 3: Post-Migration (Days 1-30)
- Keep old provider active 72h-30 days
- Reconnect CRM, project tools, website forms
- Enable MFA, disable legacy auth
- Monitor DMARC 2-4 weeks
- Decommission only after: data verified, no old SMTP dependencies, 7+ days stable
Tools: BitTitan MigrationWiz ($14/user), Cloudiway ($9-14/user), MailJerry ($9/mailbox)
Your Action Plan
This week: Start inventory. List mailboxes, aliases, DNS records. Export one test mailbox.
One month before: Lower TTL. Build destination. Run initial sync. Notify team.
Migration week: Follow Phase 2 in order. Keep both systems running. Roll back if validation fails.
Bottom line: Proper sequencing — prepare, build, sync, switch DNS, validate, hold — dramatically reduces migration risk.
