I'm sending a SOAP request to my server via Pingdom -- just put the XML content in the POST data field. When clicking "Test Check", the button greys out for a few seconds and then comes back. I've tried with SoapUI and Postman respectively, it works there -- is this possible with Pingdom at all?
OK, found the answer myself -- Pingdom can do this without a problem, I only needed to remove line breaks from the SOAP message.