How do you report a product bug to Microsoft?

Ok...let's use a little logic here....there are no issues with emails sent to many other e-mail domains; therefore, I conclude that it is not Comcast, as the are not rejecting them.  Let me include here more of the rejected email info:

Received: from resomta-po-01v.sys.comcast.net ([96.114.154.225])

    by resqmta-po-01v.sys.comcast.net with ESMTP

    id mtGIddIkVF100mtGLd5XDa; Wed, 30 Aug 2017 03:01:53 +0000

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net;

    s=q20161114; t=1504062113;

    bh=FccMEN8DD7etabk8MIJC5gRnlFMaXr3aI5YMqeWgGyY=;

    h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version:

     Content-Type;

    b=KGTrJKfsR+/qf5+KFcmNI1RXGor2yJ8LO+Nt4klBrP0fXrKmM2tRDrj50irZFsqs5

     EpUqU9cjR3Dw4A3KhUfc3+cXnN06MBdLIiSytveEb6QB3lcCdM9pXd2HqbX+BUdO2f

     MT+cnJRgyEcXuZfS+beh3QoJYq1nNxWALip+zuqLCja91ME9CJzvXbrjRr87ZSSaho

     NDgcgAzCYCLy9qmwxVTVAAD1RQoqqyo2RMYTKXm3mvllaxUbiiCClcjUUIsT59Mrr8

     VPzU0iwuQhFKreFqJHVgCNAq76TM3N85ejB/wF/3zteaxUNUudNVJpmhNes9UtKjAd

     LjUdIn3OKpSqQ==

Received: from foxtrot ([68.32.117.84])

    by resomta-po-01v.sys.comcast.net with SMTP

    id mtGKd7vurDe75mtGLdxmTV; Wed, 30 Aug 2017 03:01:53 +0000

From: "Kim and Cookie Keller" <******@comcast.net>

To: <******@centurytel.net>

Subject: Test Message

Date: Tue, 29 Aug 2017 22:01:48 -0500

Message-ID: <009501d3213c$5311dbb0$f9359310$@comcast.net>

MIME-Version: 1.0

Content-Type: text/plain;

    charset="us-ascii"

Content-Transfer-Encoding: 7bit

X-Mailer: Microsoft Outlook 16.0

Thread-Index: AdMhPDsW2pmk9FIISbO2XY64DjfhwQ==

Content-Language: en-us

X-Antivirus: AVG (VPS 170829-8, 08/29/2017), Outbound message

X-Antivirus-Status: Clean

X-CMAE-Envelope: MS4wfK5yfd3KnN0VFYr7XgMxfFFPRnxu56G+o2QK+DTsV7DpYkrbmLBq5+eu0QneFRkrT5nfgS0jTXk77J4lLm/XFR63QJIYO/YUQUwAcYUC5KYqS58RSrGE

 6zw8/n+SkUuAIuWvM9iatj/UhTp6qMU47O+/XzcW/5nejLfO0IeiTpjVE7C+qIfTpSI7owGLIqmD5Q==

Here's some good news for you - or at least giving hope. It's not Knology or others who reject your message; it's your Comcast:

Reporting-MTA: dns; resqmta-po-01v.sys**.comcast.net**[96.114.154.160]

means that this non-delivery reply was created by this Comcast server. So Comcast ensures that its customers like you don't send spam. And indeed, what you say seems likely: they may react on some header Outlook puts in the email. You definitely need to contact Comcast again, and request to escalate the issue to competent enough level. "May I ask, do you know what is MTA? no? sorry, please escalate this issue to someone who knows.". May need to repeat 2-3 times.

By the way, Mail in Windows 10 is very nice ( a hint).

Changed email format to plain text....

OK....found that Centurytel.net hosted emails are also rejected.  Here is the email I sent to a Centurytel.net customer:

******@centurytel.net

Hey Annie,

Let me know if you get this message...I am Cookie's husband....we are having issues with our email system

Kim Keller

Here is the rejected email message content:

Reporting-MTA: dns; resqmta-po-01v.sys.comcast.net [96.114.154.160]

Received-From-MTA: dns; resomta-po-01v.sys.comcast.net [96.114.154.225]

Arrival-Date: Wed, 30 Aug 2017 03:01:53 +0000

Final-recipient: rfc822; ******@centurytel.net

Diagnostic-Code: smtp; 554 5.7.1 [P4] Message blocked due to spam content in the message. 

Last-attempt-Date: Wed, 30 Aug 2017 03:01:54 +0000

Similar messages when I send to a Knology customer. 

When I log into my Xfinity/Comcast email account directly on Xfinity.net and send messages to those domains, I have no issues.  I spent about 3-4 hours working with a Microsoft Help desk person and went over all I am going over with you...no help....also worked with Comcast....no solution....Something Outlook 2016 is embedding in the message is causing it to be rejected by a number of different email domains.  Frustrating...

Can you post the exact text of Knology's non-delivery reply? where it says that it's spam. Also, if you receive similar rejects from others, those others' replies as well.

Even the fact that you are receiving it not only from Knology but from others as well, should hint you that it's probably not their collective contest with Microsoft.

Also, assuming that by "Microsoft 2016" you mean "Microsoft Outlook 2016" - try to send the same email using another mail client.

Well...first of all....it also is a problem with some other email domains...not just Knology....also....the emails I send are routine....as are those from my wife, who shares the address....we do nothing deliberate to cause Knology to think there is spam content....so there is nothing for me to adjust...what would you suggest?  It's basically a spitting contest between Microsoft and Knology...I will contact Knology and see what they say...they will probably just sluff it off as Microsoft is.  Had no issues with earlier versions of Outlook....

Wish I could get a better response for the issue.  It is frustrating.