Hi Tihomir,
your video "Develop complex jBPM processes ..." is well suitable for general questions about the designer and the underlying architecture.
In this video you create a new custom workitem for mailing purposes, down to console real execution.
A first (trivial) question concerns the connection with real email technolgy, which should be managed by a EmailWorkItemHandler somewhere.
I miss this link from the video. The shown custom workitem might be suitable for many other usages.
However it works: where is the trick ?