It is possible to receive data (POST) from an external server?

You could create a server-side script that accepts a POST and then performs the necessary work via the local services. Here is an example.

You will need to make sure your CORS configuration allows requests from the address sending the data and also that the POST requests include the API key and a session token (see this tutorial)

You can generate a "forever" session token to avoid having to re-authenticate your remote sender.