Email "" does not comply with addr-spec of RFC 2822

I'm getting this error in Log Message, When I try to complete the checkout Process
Drupal\Core\Entity\EntityStorageException: Email "" does not comply with addr-spec of RFC 2822. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->save() (line 816 of core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).