Trouble send e-mails to my zoho e-mail account.

Trouble send e-mails to my zoho e-mail account.

I have just setup my e-mail account with zoho which is admin@quinte69.ca.  

I can see that MX Tools indicates there is a DNS record error but I don't understand what is wrong with it.

If I send an e-mail to admin@quinte69.ca using my Gmail account, either through Chrome or through Thunderbird, it works.  

When I use any other e-mail account I have to send to this address admin@quinte69.ca then Thunderbird will not send it out and displays and error of: 

admin@quinte69.ca: 550 Requested action not taken: mailbox unavailable or not local

Can you help me sort this out?    How come Gmail works?  

Dan