Setup workflow based on a mapping's value

[dmaytum]

I'm trying to set up an email task in a workflow to run based on a value in a transformation. i.e. In a mapping, I have a expression transformation which calculates a value. Depending on what this value is, I may want to kick off the email task. Is there a way to read the transformation value and use it in a workflow.

Alternatively, can I cause the session to fail, depending on the transformation value.