AOL (and others?) non-delivery of Zoho messages

I see from another discussion three months ago that AOL is blocking Zoho free users. What steps are you taking to resolve this? Would it do any good for me to contact someone at AOL? Are you doing something wrong (and, if so, why aren't you fixing it?) or are the people at AOL jerks?

Details of my experience follow:

I am using Chrome and Windows 7. I have been getting a lot of messages like the one below. The emails were eventually delivered, at least many of them, for I got replies. But I can't have situations where I email someone about postponing an appointment and the message doesn't get delivered until the originally set time has passed. The vast majority of these messages have involved AOL, although there have been a few that did not.

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 Tue, 02 Feb 2016 21:53:33 -0800
from williamsgary@zoho.com [ williamsgary@zoho.com ]

----- The following addresses had fatal errors -----
[Status: Error, Address: < jimdwmsjw@aim.com >, ResponseCode 421, 4.7.1 : (DYN:T1) https://postmaster.aol.com/error-codes#421dynt1 ]

Message will be retried for 4 more day(s)

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

Received:from mail.zoho.com by mx.zohomail.com
with SMTP id 1454476109174346.3207921064766; Tue, 2 Feb 2016 21:08:29 -0800 (PST)
Message-ID:<152a5882540.f1e 71bbf52688.8077249329515062343@zoho.com >
Date:Tue, 02 Feb 2016 22:08:29 -0700
From:williamsgary < williamsgary@zoho.com >
User-Agent:Zoho Mail
To:"xxxxxxxxx" < xxxxxxxxx @aim.com >
Subject:Fwd: Re: <Redacted>
Content-Type:multipart/alternative;
boundary="----=_Part_90513_1341523021.1454476109126"

This morning, however I had three messages, all sent within a few minutes of midnight, all involving AOL, and all involving blockage, not merely delay, of my emails.

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.

xxxxxxxxx @aim.comDropped by Administrator.

Received:from mail.zoho.com by mx.zohomail.com
with SMTP id 1454383417042762.9152763621618; Mon, 1 Feb 2016 19:23:37 -0800 (PST)
Message-ID:<152a001c697.ec9 ca55928649.3278867811268737198@zoho.com >
Date:Mon, 01 Feb 2016 20:23:36 -0700
From:williamsgary < williamsgary@zoho.com >
User-Agent:Zoho Mail
To:Jim Williams < xxxxxxxxx @aim.com >
Cc:< xxxxxx.xxxxxxxx @gmail.com >, < x.xxxxxxxx @email.com >
Subject:<Redacted>
Content-Type:multipart/alternative;
boundary="----=_Part_48298_1317862514.1454383416987"

I don't think I'm doing anything incorrectly to cause this. If you recognize an error on my part, please advise me. I think the problem is with the bullies at AOL, who maybe want to discourage people from using a competitor. But is there anything you can do to persuade them that Zoho is a good actor? The problem is that I can't, really, use Zoho for most of my email, and some other provider for contacts with AOL addresses or routing. And if the problem is with Zoho, I hope you will fix it. I have really liked Zoho in most respects, and would hate to have to change. Especially if it's not Zoho's fault.

Gary Williams