Forwarded Email not valid due to "X-Original-To" field

bleggee
bleggee used Ask the Experts™
on
FIRST, THANK YOU IN ADVANCE FOR ANY HELP ... I REALIZE THAT THIS IS A BIT DETAILED, THANKS FOR READING AND TRYING TO HELP:
I use a 3rd party cloud application (let's call it "theirdomain.com") that "accepts" email that is sent directly to them, but "ignores" emails that are cc'd, bcc'd,, or forwarded to them. It is *not* Open Source, so I am looking for a workaround.

I ran some tests, and see that the only difference in the Raw Email between the "accepted" EMail and the "ignored" Email, since it was forwarded to them, is this:

RAW EMAIL ACCEPTED BY THEM (Was sent to "john@theirdomain.com"):
X-Original-To: john@theirdomain.com
Delivered-To: john@theirdomain.com

RAW EMAIL IGNORED BY THEM (Was sent to me@mydomain.com, which is forwarded to john@theirdomain.com):
X-Original-To: me@mydomain.com
Delivered-To: john@theirdomain.com

Is there a way to change/spoof this "X-Original-To" ? I want to forward these Emails so that MY customers only see mydomains.com, and do not reveal the name of my provider (theirdomain.com). If he Spammers can do this, there must be a way!
Or is there another alternative ... send them Email thru a Web Form that controls the contents of the "X-Original-To" field?
Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
Commented:
P.S. My Email sending server is Linux/LAMP, Courier IMAP, PostFix Email server, I have Server Root Access.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial