This is pretty alarming, and I am surprised they'd go this far
Essentially, by encrypting the URL, there is no way to separate the tracking part from the actual URL.
If you posted a facebook link on poast, facebook would know it comes from you, your IP or account, they'd know who posted it.
And if you click on such a link, they automatically know where you came from even if the browser strips referrals.
This is why I'm glad I use eg. nitter for twitter and don't visit the actual site anymore. They could easily implement that too and track you. Do not post direct social media links. Post archives or similar alternatives.
Gregory's Server