Yahoo and Hotmail Reporting 421, 4.7.0 [TSS04]

Yahoo and Hotmail Reporting 421, 4.7.0 [TSS04]

Looks like Zoho has some spam activity going through their systems that is adversely affecting our email. Please investigate and clear any grey lists that have resulted.

Example:

Subject: Mail Delivery Status Notification (Delay)
Date: 12/23/19, 10:44 AM

This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Mon, 23 Dec 2019 07:44:37 -0800

    ----- The following addresses had fatal errors -----
   [Status: Error, Address: <mxxxxx1@yahoo.com>, ResponseCode 421, 4.7.0 [TSS04] Messages from 136.143.189.10 temporarily deferred due to user complaints - 4.16.55.1; see https://help.yahoo.com/kb/postmaster/SLN3434.html]

Message will be retried for 4 more day(s)


Reporting-MTA: dns; mx.zohomail.com
Arrival-Date: Mon, 23 Dec 2019 09:59:24 -0500
Original-Recipient: rfc822; mxxxxx1@yahoo.com
Final-Recipient: rfc822; mxxxxx1@yahoo.com
Status: 421
Action: failed
Last-Attempt-Date: 23 Dec 2019 15:44:37 GMT
Diagnostic-Code: 


    ----- Transcript of session follows -----

 Received:from [192.168.1.195] (pool-xxx-xx-xxx-xx.clppva.fios.verizon.net [xxx.xx.xxx.xx]) by mx.zohomail.com
    with SMTPS id 1577113165300626.8640448514706; Mon, 23 Dec 2019 06:59:25 -0800 (PST)
 Date:Mon, 23 Dec 2019 09:59:24 -0500
 User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
 Subject:Re: Your Store Cash at TouchUpDirect will expire soon
 Content-Type:text/plain; charset=utf-8; format=flowed