* The add-on collects no information besides what it includes in the generated link
* The generated link contains some information about the email but not the email body.
You can configure in the options what should be included.
* Who has the link only gets the message-id and the optionally included data.
If the person does not have the email yet, they will not be able to get it using the link.
* Clicking on the link does not transfer information about the email (even the data included in the link)
to the server hosting the landing page. (Unless the server serves a malicious webpage that transfers information back.)
* You can host your own landing page if you prefer.