Error message: Your migration failed checking credentials. Mailbox does not exist. Error: ErrorNonExistentMailbox
Cause: Some defective IMAP servers may list folders but later fail to return content from these folders. This typically affects IMAP implementations that are unable to handle special characters in folder names. This error will result in a failed migration because an entire folder cannot be processed.
- A defective IMAP server may list a folder called "A - B", but fail to return content for this folder because of the special character ("-" in this example).
- The problem may also affect folders having trailing spaces. For example, a defective IMAP server may list a folder called "A/B ", but fail to return content for this folder because of the trailing space.
- The mailbox does not exist and needs to be created.
Resolution: There are several options for resolution, depending on the cause.
- Check your IMAP system for upgrades.
- Specify a folder exclusion filter to exclude these folders from the migration.
- Check that the end user email address is entered correctly in MigrationWiz and (if using admin credentials).
- Check that the admin email address is entered correctly in the endpoint.
- Ensure the the end user has a licensed mailbox associated with it in the customer's environment.
- If using an admin without impersonation, ensure the admin has a mailbox.
- If using admin credentials without impersonation, check the admin has the necessary permissions as outlined in this Help Center article: How do I create an administrator account in Office 365, and then use this during migration?