Please find the attached Custom Plugin to read mail attachment file name from mail source activity. The name of the mail attachment is stored in a variable named “attachedFileName” after this Custom Plugin. This custom plugin can be used anywhere in the process flow.
This variable can be further used in the Process Flow for over-riding any File name parameter.
For example: If you want dynamic mail attachment name to be the File target name, then use a Put Context-Var activity before target and over-ride the File Name with following value “$$attachedFileName$$”. See image below for more info: