Unable to send emails to former members

I sent an email from my personal email address to former members: formermembers@cutlerbaytoastmasters.com and received a message doesn't exist.  See below error message.  What can be done so I may send events information using former and guests email blasts.  Thank you.

My name is Betty Ortiz-Valdes, Website Administrator for Cutler Bay Toastmasters, Club#1412303Your message to formermembers@cutlerbaytoastmasters.com couldn't be delivered.formermembers wasn't found at cutlerbaytoastmasters.com.Office 365 How to Fix It The address may be misspelled or may not exist. Try one or more of the following:·       Send the message again following these steps: In Outlook, open this non-delivery report (NDR) and choose Send Again from the Report ribbon. In Outlook on the web, select this NDR, then select the link "To send this message again, click here." Then delete and retype the entire recipient address. If prompted with an Auto-Complete List suggestion don't select it. After typing the complete address, click Send.·       Contact the recipient (by phone, for example) to check that the address exists and is correct.·       The recipient may have set up email forwarding to an incorrect address. Ask them to check that any forwarding they've set up is working correctly.·       Clear the recipient Auto-Complete List in Outlook or Outlook on the web by following the steps in this article: Fix email delivery issues for error code 5.1.1 in Office 365 , and then send the message again. Retype the entire recipient address before selecting Send.

Your domain DNS is not setup correctly

missing

mail.cutlerbaytoastmasters.com. 3600    IN    A    50.19.253.65
cutlerbaytoastmasters.com. 3600    IN    MX 10   mail.cutlerbaytoastmasters.com

delete

cutlerbaytoastmasters.com. 3600    IN    MX    0 smtp.secureserver.net.
cutlerbaytoastmasters.com. 3600    IN    MX    10 mailstore1.secureserver.net.


 

Thank you for the quick response.  Where do I go to setup domain DNS correctly - is it my system or the website?  Where do I enter Missing information.
I appreciate your assistance.
Betty

Whoever bought the domain name needs to go where the DNS is hosted and make the changes.
Your domain registrar looks like it is www.godaddy.com