PI 7.0 -- Not getting the attachment after using adapter module SetAttachmentName

In order to dynamically name the attachment in the mail receiver adapter, I deployed the module SetAttachmentName (as shown in wiki Adapter Module PI 7.0 Set Attachment Name - Process Integration - SCN Wiki) into my PI and used it in the my mail receiver comm channel before the mail module. But now when I test it, the whole attachment is coming inside the body of the email and not as an attachment. I have checked in scn blogs but did not find any relevant material for my issue. Did anybody face such an issue while using this custom module?