Mail migration warning in Plesk: Unable to create object

Symptoms

Migration fails with error:

Execution of /opt/psa/admin/plib/api-cli/domain_pref.php --update example.com -sign_outgoing_mail false -ignore-nonexistent-options failed with return code 1.
Stderr is
An error occurred while updating domain settings: Unable to create object:

Cause

Outgoing mail limits are not enabled.

Resolution

1. Login to Plesk
2. Go to Tools & Settings > Mail Server Settings > Turn on limitations on outgoing email messages and enable outgoing mail limits.
3. Re-sync mail content