Hi, I do not believe that this is an OOB deliverable and the core issue with scripting attachments to outbound emails is identifying which attachments from the task should be sent with each email.
I suspect the issue here is process, and the best OOB solution would be for your end users to utilize the quick message functionality when they want to send attachments. Composing emails with quick messages (servicenow.com) Any attachment sent via quick message will then also be added to the task as an attachment.
