Common Migration Strategies

Here are the most common migration strategies that are performed:

Big Bang Migration:

A single pass migration strategy that will move the entire mailbox in one pass after MX records are cutover.
A typical scenario consists in cutting over on a Friday evening and migrating during the weekend.


  • Cost-effective.
  • Simplest to implement.


  • Migration may potentially not complete in time for various reasons.
    • Users accessing the new system may not have access to all their data when work resumes.
    • Any items created during or after the migration may be missed by a single pass.
    • Downtime may occur for some users if migration fails or takes too long.

Pre-Stage Migration:

A multi-pass migration consists of pre-staging a majority of the data prior to cutover and doing a Full (Delta) Pass after cutover.


  • Majority of data is available at time of cutover.
  • Mitigate migration risks in which the majority of data will be available regardless of availability of source server at time of cutover.


  • Will not propagate updates, deletes, or moves of the items previously migrated in the first migration pass.

How do I configure a multi-pass migration?

Quick-Switch Migration

A quick-switch migration consists of pre-staging only the newest emails. New emails are accessible immediately at time of cutover by users and the remaining data is backfilled over time.


  • Initial migration is quick.
  • Time between cutover and data availability is short.


  • Not all data is available at time of cutover for end users.

How do I configure a Quick-Switch Migration?​​​

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