osCommerce email problems PLEASE HELP!

Email is not working correctly on my osCommerce installation. Before you reply, read everything that I have to say.

1) This is hosted on a linux server.
2) Transport is set to "sendmail" and I have tried "SMTP" as well
3) line feeds is set to "lf" and I have tried "crlf" as well
4) Emails are set to "true", they are turned on
5) There is an email address installed for the site owner and for the "from" field
6) The email_test.php contribution 1595 has been installed and tested.

What I have been able to confirm.
1) the Email address works as a functional email address to send and receive mail for everything BUT osCommerce
2) When sending an email from the test script and osCommerce, email is transported, I get the verification that it has sent.
3) Email will go without any trouble to Yahoo mail and Hotmail as well as other web based email addresses
4) Email will NOT go to ISP hosted addresses such as user@yourdomain.com
5) I have contacted the hosting company and they have verified that sendmail is functioning properly on port 25, but the mail is being rejected with the following error:
xdelay=00:01:06, mailer=esmtp, pri=30329, relay=nymx-2.nyroc.rr.com. [24.92.226.31], dsn=5.6.0, stat=Data format error
Feb 18 11:14:04 ns sendmail[797]: i1IGCvmB000795: i1IGE4mB000797: DSN: Data format error
Feb 18 11:14:04 ns sendmail[797]: i1IGE4mB000797: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=31454, dsn=2.0.0, stat=Sent

Emails go out, but they are rejected.

6) The ISP claims that the script needs tweaking and there is nothing wrong with the server or it's settings.

I need the following:

1) A solution
2) Something specific to tell the hosting company if it IS the server that is causing this.
3) Something specific to do to the code if it's NOT the server.

There are HUNDREDS of posts about this and similar problems all over the internet in forums such as this and no one to date has been kind enough to post the solution if they have found it. I will post the solution if one exists.

I need help and at this point, I need it soon.

Please don't ask if I have things like sendmail and lf set, or if it's set to be on, that was days ago. At this point I know that mail is going to SOME places, why not others? Is there something about the headers that is causing them to be rejected by ISP email hosts? If so, what can be done about it?

Any help will be so much appreciated you can't even imagine.

Thanks in advance.

 

 

 

 

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