Onboarding | Project Phases | Best Practices | Glossary of Key Terms

Mailbox Migration Methodologies

Transend’s mailbox migration methodologies are designed to ensure an efficient cutover, with an optimized user experience. As a result, we offer two default mailbox migration methodologies: A Staged Migration and a Post-Cutover Single-pass Migration.

Note: If your Agreement is dated February 6, 2026 or prior, it included a legacy mailbox migration methodology, which is a 3-Stage migration approach. Effective February 7, 2026 the 3-Stage migration approach was replaced with a 2-Stage migration approach.

Staged Migration

For most projects, this is the recommended migration methodology.

The Staged Migration approach is designed to ensure most email data is migrated before the Cutover, allowing a smoother transition at Cutover. User disruption is minimized by having nearly all email data available when users “go live” in their new target account.

  • Stage-1 – Pre-Cutover migration includes all email in a mailbox
  • Cutover – Update DNS records to change mail routing (Users “go live” in target)
  • Stage-2 – Post-Cutover migration includes Stage-1 email delta (new/changed messages), Calendars, Contacts, Tasks

Pros – Enables a smoother, more seamless user experience at Cutover. Minimizes disruption by having the majority of mailbox data available at go-live.

Cons – Depending on the number of users and data storage, Stage-1 may extend the timeline before Cutover can occur.

Post Cutover Single-pass Migration

Alternatively, for customers who want mail routing to the new platform updated as quickly as possible, Transend can perform a Single-pass migration of all data after email routing is updated and users are live in the new platform.

  • Cutover – Update DNS records to change mail routing to target (Users “Go Live” in target)
  • Single-pass migration – Perform Single-pass migration of all data in scope

Pros – Allows Cutover to occur as quickly as possible. Reduces upfront migration time prior to go-live.

Cons – Users “go live” in the target platform without access to legacy data initially. Legacy data becomes available only after the Post-Cutover migration completes.

If your target platform is already live (i.e. users send/receive mail from the target already) and no mail routing changes are required, then a Single-pass migration is the recommended migration methodology.