Running 5.1.5, and working with workflow schemas and looking to update the subject for the 'Workflow started' email - but can't find it under custom messages for the schema or workflow step.
Is it customisable? And if so from where?
Added in 5.2.0.0
https://squizmap.squiz.net/matrix/5977
Alternatively you could try and use a trigger send email action and use that instead?