Mimecast Synchronization Engine: Migrating Mailboxes Between Exchange Environments

Document created by user.oxriBaJeN4 Employee on Mar 13, 2018Last modified by user.oxriBaJeN4 Employee on Apr 2, 2019
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This guide describes how to migrate mailboxes from one Exchange environment to another in the Mimecast Synchronization Engine, in order to prevent replicated mailboxes.


To prevent inconsistencies being introduced that effect an end user's ability to access archive folders in one of Mimecast's end user applications, the following has been prepared for your consideration.

  • Before migrating, ensure the user account(s) who’s mailboxes are to be migrated, aren't in any Mailbox Folder Replication tasks that target either the new or existing Exchange environment.
  • After the source mailboxes have been migrated (e.g. access to the migrated mailbox has been restored to the end user) add the user accounts to a group associated with a Mailbox Folder Replication task. Ensure it targets only mailboxes that have been fully migrated in the new Exchange environment. 


Where the above isn't done, problems can arise if Mimecast Synchronization Engine replicates the new mailbox object from the new Exchange environment prior to, or during, migration of the mailbox. The end result can manifest in various ways, but has been known to present itself as:

  • Partial access to a subset of folders that can be rendered.
  • Inability to access or view any archive folders via an end user application.