Mendelson AS2 is one of the widely used AS2 clients, and is also the unofficial AS2 testing tool that we use here at AdroitLogic (besides OpenAS2, etc).
While Mendelson does offer quite a lucrative handful of features, one needs more flexibility in order to integrate it into actual testing cycles—such as programmatic test automation of an existing solution like AS2Gateway. https://goo.gl/1JFLbG #DataIntegration #ML
