On Demand Migration for Email (ODME) best practices (4320223)

1.- Ensure the source endpoint allows access to the ODME IP Public addresses. These details are listed in the "Migrate" section within an ODME plan:

Note: These IP addresses can change, please verify them directly from the ODME Portal.

2.- It is very important to realize that ODME is not a sync-and-switch solution or a solution that updates deletion/modifications from the source to target. If the users are going to keep accessing their source mailbox during migration then the recommended option is to include a one-time pre-migration using date filtering (e.g. 01/01/1970 – 10/31/2015) to stage mail data to the target mailbox. Then a subsequent run to migrate the remaining mail (e.g. 11/01/2015 – present) and the calendar, tasks and contacts. This approach can streamline the transition and eliminate the reliance on migration of deletions & modifications. 

Click here to see more details regarding choosing a migration type.

3.- ODME does not create the target mailboxes. You need to ensure target mailboxes are created prior to migrate.

4.- When migrating archive to archive ensure both source and target check-boxes are checked:

5.- ODME issues a license per user and keeps records of each licensed user by their source SMTP address. If the SMTP address is changed once the user has been migrated for the first time, ODME will issue another license for the same user.

6.- In ODME, for each Microsoft-based email service, there is no longer a limit to the number of mailboxes migrated concurrently per plan. By default is set to 500, but this value can be changed to unlimited:

Note: Please be aware that there might still be some issues not related to ODME when migrating too many mailboxes at the same time. For instance source or target environment may not be able to keep up too many mailboxes being migrated simultaneously while still being responsive and available to their users. To avoid this problem the suggestion is to limit the number of mailboxes migrated concurrently in a migration plan using above feature.

7.- The total number of running plans under the same administrator account is no longer limited.

Note: Please be aware that ODME uses PowerShell to configure the forwarding options (Forwarding new items as they arrive and Turn off existing forwarding) for Exchange/O365. If a migration plan has one or more of these options enabled, when it starts, it opens a PowerShell connection to configure the enabled options. If you have too many plans configured under the same administrative account and they start approximately at the same time, you can hit the ‘PowerShellMaxConcurrency’ throttling limit for this account. In this case, the plan hit that limit will be rescheduled to start later, when a PowerShell connection is available, and the corresponding message will be displayed in the plan. Please consider to specify a different administrative account for paused plans if you need them to start immediately. Note that the connections under the same account may be done outside the product. 

8.- By default a single mailbox can be migrated a maximum of 10 times successfully. After this limit is reached ODME will not migrate the mailbox again.

Note: A request can be sent via a service request to increase this limit.

9.- If the number of processed items is bigger than the number of estimated items, it is very likely that items in the target are being archived by policy between consecutive migrations. It is recommended to stop archiving during the duration of the migration project.

10.- Source and target Mailbox size mismatch. A size mismatch should not be an issue as long as the number of items in the source and target match. If the number of Exchange items is bigger than the Gmail items, it is very likely that ODME option "Create a folder for each label and copy messages into the corresponding folders" is being used.

11.- ODME is designed to use "Application Impersonation" to migrate mailboxes. Full Access permissions will not work with ODME.

12.-  There is no restrictions associated with the number of admin accounts needed to migrate the user mailboxes.  A single account with Application Impersonation is required.

13.- Any email received after the mailbox has been processed, will not be migrated until you run the migration again. During the final migration pass, ODME should be used to set forwarding on the source mailbox, so that any new mail received is forwarded to the new target while the migration is ongoing.

14.- ODME templates, click here to get further details.

15.- An "End User Notification" can be used to inform individual users when their migration has been successfully completed:

Preparing your source email service for migration:

• Google Apps
• Sun ONE/iPlanet
• Novell GroupWise
• Microsoft 2007/2010/2013
• Microsoft Office 365
• POP/Windows Live Hotmail
• IMAP
• Zimbra

Preparing your target email service for migration:

• Microsoft 2010/2013/2016
• Microsoft Office 365

Click here to access the ODME online User Guide.
Click here to access the ODME online Release Notes.
Click here to access the ODME online Known Limitation details.
Click here to access the CPUU online User Guide.

- Click here to get details regarding easy steps to use ODME.
- Click here to find all the options to subscribe to the ODME Service.

Useful KB articles:
How To: Step by step guide to a tenant to tenant migration with ODME and CPUU