How to sned the document by email to NVC

[gloria7 0]

I am at the stage where i have paid AOS and IV fees submitted DS260 and have collected all the scans of the IV and AOS package documents. The fist time i have send IV and AOS document by eamil to NVC on 3rd april 2018, i didnt get any respond from NVC in next 5 days, so i called to asking if they received my email, but they got nothing, i sent them again on 9th april 2018, and i called this morning but they still got nothing with my case. 

i can't figure out are there something wrong with the email what i sent, Why NVC can't receive my email , here is how i did in email:   

Type my case Number in subject line ,Name the files as:CaseNumber_FirstName_LastName__File_Description.pdf, also make sure none of the PDF files are secure/password-protected and every PDF files are less then 5MB.