How to define due date only during work day and trigger mail of over due?

[RadhikaNair]

Any help or assistance is really appreciated

[Damir-Kovacevic]

You should use script task before user task, in script task do calculation for dueDateValue only during work day and create proces variable. You can create proces variable used in script task expresion: execution.setVariable('dueDateValue', dueDateValue).

This process variable dueDateValue you can put on boundary timer on user task, and boundary timer link with activiti mail component or link with script task send mail through rest service.