Facing issue while submitting the Invoice on Dell Offer site.

i ordered a Dell 5420 laptop on dell official website. While applying the Dell Offer service I submitted all the documents. After someday I was getting one mail like Offer has on hold because Invoice is missing. And also, they provided a Dell offer team member mail id. But when i try send a mail, the dell SMTP server completely blocking my mail id. I tried to contact through phone but no one pick the phone. Could anyone  please help me to solve this issue.