Migration Services

Email Migration

Migrate mailboxes, calendars, and contacts between Google Workspace, Microsoft 365, Exchange, and on-prem — with zero mail loss and minimal downtime.

Talk to an email migration specialist

Overview

Email migration is high-stakes because every user notices immediately if something goes wrong. Lose an email, break a calendar invite, or mess up folder structures and you have a building full of angry employees on Monday morning. Most email migrations fail because of poor planning around DNS cutovers, mailbox size limits, and shared mailbox handling.

CB4UHost migrates email between Google Workspace, Microsoft 365, Exchange Server, and on-prem systems. We use vendor migration tools (Google Workspace Migration, Microsoft FastTrack) plus third-party tools (BitTitan, Quest) when the vendor tools aren't enough.

We handle mailboxes, calendars, contacts, shared mailboxes, distribution lists, and archive data. We plan the DNS cutover (MX records, SPF/DKIM/DMARC) to minimize mail delivery delays, and we monitor for 7 days post-migration to catch any stragglers.

Every migration ends with user communication templates, admin runbooks, and a 7-day monitoring window.

What's included

Mailbox inventory + sizing

We inventory mailboxes, shared mailboxes, distribution lists, and archive data.

Migration plan + cutover

Detailed plan with DNS cutover timing, user communication, and rollback.

Pre-stage migration

We pre-stage mailbox data (often 1-2 weeks before cutover) so the final delta sync is small.

DNS cutover + monitoring

MX record, SPF/DKIM/DMARC cutover with 7-day monitoring for delayed mail.

User communication

Email templates, FAQ, and end-user support runbook for the migration week.

Post-migration support

7-day monitoring window plus admin and user runbooks.

How we work

1

Inventory + planning

We inventory mailboxes and plan the migration strategy.

2

Pre-stage

We bulk-migrate mailbox data 1-2 weeks before cutover.

3

Delta sync + cutover

We sync the delta (new mail since pre-stage) and cut over DNS.

4

Monitoring

We monitor for 7 days to catch delayed mail or sync issues.

5

Handover

We hand over admin runbooks and user documentation.

FAQ

How much downtime will users experience?

Typically 30 minutes to 2 hours during the DNS cutover window (usually scheduled overnight or on a weekend). Users can still send/receive on the old system until cutover, then on the new system after. Pre-staging means the actual cutover is small.

Do you migrate archives and PST files?

Yes. We migrate Exchange Online Archives, on-prem archives, and PST files to the new system. PST ingestion can be slow for large archives — we'll estimate during planning.

What about shared mailboxes and distribution lists?

We migrate all of them — shared mailboxes, room/equipment mailboxes, distribution lists, mail-enabled security groups, and contacts. We map them 1:1 unless you want to restructure.

How do you handle mail delivery during DNS propagation?

We keep the old MX records active for 48-72 hours after cutover and configure mail forwarding at the old provider. Any mail that hits the old provider during DNS propagation gets forwarded to the new provider — zero mail loss.

Ready to talk?

Tell us about your project. We'll come back with a scoped proposal and a fixed-fee quote.

Talk to an email migration specialist