I am sending an email with PDF Attachment through a workflow. The user should not able to Edit the document which he received by email. He should open and download and review but should not Edit the document before download it. Is there any option to lock the email document?
I don't think its possible without using any third party API. Once user receive the PDF at there end they can do anything they want.
Password Protect A PDF Via API For example you can use these API to prevent any modification (It looks like a paid api you can try google to find any free api).