Social sites such as Facebook can sometimes display if a message has been sent via a third party platform such as Sendible.
This is not always displayed but is more likely to be displayed if for example you are logged in as an admin on Facebook or if you're viewing Facebook from a mobile device.
This is applied to all third party Apps and cannot be fully removed. We can provide generic Apps if this is still a concern for you but these Apps are only included with our White Label solution.
If you would like to discuss our White Label solution, please contact our sales team by emailing firstname.lastname@example.org.