We are V6.1. We email PO's as a PDF attachment using QTMMSENDMAIL. Some vendors(not all) do not get emails from the iSeries using this API, but they do get emails thru outlook, or a third party product called iMail. I have tried changing the from address to various other addresses - none have worked so far. I'm getting a bounce back like this: 

NOT ABLE TO DELIVER MAIL TO SOME/ALL RECIPIENTS.

REPLY CODES WITH FIRST DIGIT = '4' OR '5' ARE ERROR REPLIES.

ERRORS THAT DO NOT HAVE ERROR REPLY CODES MAY EXIST.

HOST (hostname) NOT ABLE TO DELIVER MAIL TO FOLLOWING RECIPIENT(S):

   <vendoremailaddress>

RETRIES EXHAUSTED WHILE ATTEMPTING TO CONNECT TO REMOTE HOST vendordomainnname.

             ** TEXT OF MAIL FOLLOWS **

To: VendorName/TEST PO <vendoremailaddress>

From: OurCompanyName <mycompanyemailaddress>

Date: Thu, 12 Jan 2012 10:43:54 -0600

Subject: PO#:9516095-/TEST PO

MIME-Version: 1.0

Content-Type: multipart/mixed; boundary="--=.=2012-01-12-10.43.50.144000"

----=.=2012-01-12-10.43.50.144000

Content-Type: text/plain

TEST TEST Note: This is a Purchase Order Via E-Mail! From CompanyNAME.

----=.=2012-01-12-10.43.50.144000

Content-Type: application/octet-stream; name="9516095V_2012-01-12-10.39.00.673000.PDF"

Content-Disposition: attachment;filename="9516095V_2012-01-12-10.39.00.673000.PDF"

Content-Transfer-Encoding: base64

JVBERi0xLjQKJcnDxOIKJUlDRFMyUERGIFZlcnNpb24gMSBSZXZpc2lvbiAyMSBpCiUgSUJNUFND

MjAwIPHwbeXi1tfWbfn18fbw+fXlbfLw8fJg8PFg8fJg8fBL8/lL8PBL9vfz8PDwQEBAQEBAQEBA

Any ideas/suggestions would be greaty appreciated.

Larry