Problem in 3 Cs => email reported as spam

Hi,

We have set 3 Cs Communication to send student's exam card.

But then we have problem, the email that we sent is reported as spam. We make communication for about 300 students.

Now I want to run for 800 students to send their grade report, but I'm affraid that email will be considered as spam and our email which have domain uph.edu will be block and can't send email to other email.

This is the original header from what we generate:

Return-Path: opcs2888@uph.edu Received: from epistle.uph.edu (LHLO epistle.uph.edu) (122.200.2.40) by epistle.uph.edu with LMTP; Wed, 10 Dec 2014