This article describes how delta migration works.

Delta migration during a Mail Migration

Cloudiway migration internally stores a reference to all items it migrates.

  • For mails, it stores the MessageId contained in the header or the unique IMAP ID.
  • For contacts or calendars,  it stores the provider internal id (ie Office 365 or Google unique id)

When you remigrate a mailbox (delta pass), items that have already been pushed are not migrated again.

The delta pass mechanism ensures that no duplicate content is created in the target.

Special Notes: A migrated item is never reprocessed, delta migration is not equivalent to synchronization.
Changes to already migrated emails and contacts are not propagated again.
However, changes to appointments (updates, deletions) are propagated.

  • Cloudiway migration does not perform any deletion or renaming in the target mailboxes. Consider that a delta pass is an “Add mode” only.
  • If a user deletes a mail in a folder between 2 passes, the deleted email will remain in the target mailbox.
  • If a folder is deleted in the source between 2 delta passes, the folder is not deleted in the target.
  • Mails moved between 2 delta passes are not moved to the target.

Calendar processing

The calendar migration engine works as a synchronization engine. Depending on the scenario, updates and deletions of appointments can be propagated during delta passes.

See more about calendar migration in this article.

Contacts processing

During a delta pass, new contacts are migrated. Deletions and modifications are not propagated.

Tasks processing

During a delta pass, new tasks are migrated. Deletions and modifications are not propagated.