Sender address rejected: MX or A record not found]

Can anyone help resolve this issue? I have already sent emails to Zoho and they have not replied(2 emails sent within last week). Great customer service heh...

I have my .xyz domain registered with namecheap and have configured CNAME, SPF and DKIM as per the Zoho instructions. However, I still have some people not receiving my emails, and I get the following error message when I send to Canadian governement employees.

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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, 14 Mar 2017 05:44:12 -0700
from xxx@xxxxxx.xyz [xxx@xxxxxxx.xyz]

----- The following addresses had fatal errors -----
[Status: ERROR, Address: <xxx.xxxxe@aadnc-aandc.gc.ca>, ResponseCode 450, 4.1.8 <xxx@xxxxxxx.xyz>: Sender address rejected: MX or A record not found]

Message will be retried for 4 more day(s)

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The person eventually gets my email, usually a day or two after I have sent it.

Does anyone know what setting would cause this?

Thanks