Postback URLs are used a lot in CPA Networks and I particularly prefer using these over using pixels. In Clickmagick, they have what they call a “Postback URL Builder” under the “Tools” section. There are even some offers where ONLY postback URLs can be used… which makes it even more a necessity! So that would be really cool to see this being added asap! 
We will do this as soon as possible. Thnx for feature request!