Although I got an requirement to send mail to user with this attachment on SAVE of the Inquiry Change Screen only..
I am able to trigger the Mail but I am not finding the suitable Enhancement for this case.
Somehow I managed to find user exit USEREXIT_SAVE_DOCUMENT in include MV45AFZZ BUT IT DOES NOT GET TRIGGER ON SAVE OF ATTACHMENT BUT ONLY GETS TRIGGER IF I MADE ANY CHANGES INQUIRY (WEIRD AS IT DOESN'T TREAT ATTACHMENT AS A CHANGE TO SALES DOCUMENT).
As you can see in below image I am trying to create an attachment for an Enquiry in SAP ECC system.
Would appreciate any comment.