Error: Not all of the selected mailboxes have been mapped to destination mailboxes

Error:

Not all of the selected mailboxes have been mapped to destination mailboxes

Cause:

When a mailbox migration is created, all or some mailboxes are selected and on the source server and Start Migration has been initialized, Cloud Migration platform tries to map those mailboxes to the ones with the same username on the destination server. If some of them don't exist on the destination or if they are named differently, error: Not all of the selected mailboxes have been mapped to destination mailboxes will appear.

Note: Auto-mapping will map mailboxes even if they are of a different type. E.g. If a regular mailbox with the username Jon.Smith exists on the source server and on the destination server there is a shared mailbox (or room, equipment...) with the same name, it will be automatically mapped.

Resolution:

On the first tab Mailbox Mapping check the mailboxes in the bottom of the page whose Destination field is empty.

In order to continue with this migration all destinations must be filled. There are four options for this:

Create those users on the destination server and click on Reload destinations

Click on Remove all unmapped in order to remove all mailboxes which don't have a mapped destination

Remove each mailbox individually by clicking on the X on the right hand side of it

From the drop-down list select some other available mailbox and use that one as the destination

If you wish to reset mapped mailboxes to the begging state, click on Reset mappings.

After all mailboxes which didn't have populated destination filed have been removed or filled, migration can be resumed by clicking on Start Migration button.