Zoho customers unable to send mail to aleyant.com

We are not a zoho customer ourselves, but several of our customers have recently transitioned to zoho mail. They are reporting to us that it is impossible to send mail to aleyant.com through zoho's SMTP servers. Here is an example bounce message. Our email address (the destination) is bolded.

The original message was received at Wed, 02 Sep 2015 10:27:47 -0700
from aaron@taylor-madeprinting.com [ aaron@taylor-madeprinting.com ]

----- The following addresses had fatal errors -----
[Status: Domain Not Resolved, Address: < support@aleyant.com >]

Message will be retried for 4 more day(s)

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

Received:from [10.0.0.27] (70.97.64.142 [70.97.64.142]) by mx.zohomail.com
with SMTPS id 1441212139454653.9468341239369; Wed, 2 Sep 2015 09:42:19 -0700 (PDT)
Message-ID:< 55E726E2.5020306@taylor-madeprinting.com >
Date:Wed, 2 Sep 2015 09:42:10 -0700
From:Aaron < aaron@taylor-madeprinting.com >
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
Thunderbird/38.2.0
To:Aleyant Systems Support < support@aleyant.com >
Subject:Re: [1BE-1D70B797-082B] Proofing Image
Content-Type:multipart/alternative;
boundary="------------080109070300030906030100"

Our DNS is quite definitely working; Google DNS 8.8.8.8 accurately resolves MX for aleyant.com:

C:\>dig -t mx @8.8.8.8 aleyant.com

; <<>> DiG 9.10.2-P2 <<>> -t mx @8.8.8.8 aleyant.com

; (1 server found)

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36994

;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:

; EDNS: version: 0, flags:; udp: 512

;; QUESTION SECTION:

;aleyant.com. IN MX

;; ANSWER SECTION:

aleyant.com. 3599 IN MX 10 mail.aleyant.com.

;; Query time: 76 msec

;; SERVER: 8.8.8.8#53(8.8.8.8)

;; WHEN: Thu Sep 03 16:25:20 EDT 2015

;; MSG SIZE rcvd: 61

C:\>dig -t A @8.8.8.8 mail.aleyant.com

; <<>> DiG 9.10.2-P2 <<>> -t A @8.8.8.8 mail.aleyant.com

; (1 server found)

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11363

;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:

; EDNS: version: 0, flags:; udp: 512

;; QUESTION SECTION:

;mail.aleyant.com. IN A

;; ANSWER SECTION:

mail.aleyant.com. 3599 IN A 184.154.81.6

;; Query time: 69 msec

;; SERVER: 8.8.8.8#53(8.8.8.8)

;; WHEN: Thu Sep 03 16:25:32 EDT 2015

;; MSG SIZE rcvd: 61

In addition we receive mail from hundreds of other users every day without any issue.

taylormadeprinting.com is only one zoho customer that has this problem. Another one is salzmanfamily.org.

Please help us with this issue.