After selecting all the documents in the basket and then send email results in an error - invalid object type id
This is a known issue in versions 15.x.x. The error is a result of checking the Basket folder to select all the documents to be sent from the basket.
This issue has been fixed in version 16.4.2.
Before upgrading to 16.4.2, do not select the Basket folder. Instead, select all the documents to be sent by checking their respective checkboxes.