We are bit confused as we are getting around 100 bounces on our newsletter however it doesn't show up as a bounce within the Acymailing Enterprise backend.

We have a 10/10 spam score and the DKIM and SPF are all setup correctly. Here is the bounce message:

From: Mail Delivery System <Mailer-Daemon@chi-node47.websitehostserver.net>
Date: Wed, Jan 16, 2019 at 10:30 PM
Subject: Mail delivery failed: returning message to sender
To: <info@ojonline.net>

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

stephanie-k-lynch@uiowa.edu
host uiowa-edu.mail.protection.outlook.com [104.47.48.36]
SMTP error from remote mail server after RCPT TO:<stephanie-k-lynch@uiowa.edu>:
550 5.7.606 Access denied, banned sending IP [184.154.72.20]. To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to http://go.microsoft.com/fwlink/?LinkID=526655 (AS16012609) [CO1NAM05FT060.eop-nam05.prod.protection.outlook.com]

We tried to delist ourselves a number of times however we never receive the email that it says it will send us. Here is their message:

Step 2: An email with instructions has been sent to info@ojonline.net. Check your Inbox and your junk folder for the email. If you don't see the email within one hour, start over at Step 1 but use a different e-mail account.

Can you advise on the following:

Why is this email bouncing and yet it doesn't show on Acymailing?
How to fix this bounce issue?

Thanks,

Stan