We have a new server with a fresh install of Zpanel software. All domains we host (about 30)and DNS have already been moved to the new server. We also have set up all email accounts for the domains but have not yet made them live (email currently is on another locally hosted server using Imail. One of the domains had a form that uses sendmail php to email the recipient. She however was receiving the inquiries. Came to find out rather than using the MX record specified on the DNS in the new server it was automatically looking for it locally on that server. Therefore the email inquiries were going to that email address on the new server rather than the old. Further testing was done by sending a test email from the webmail of the test domain to another domain address. Same thing happened; instead of checking MX records the email was sent to the account on the local machine. Is there anyway to force Postfix to use MX records first rather than trying to send it locally?

I dont understand all things you wrote but you should check your zones and your mail server's dns settings. And also your named.conf is it listening for queries on interface where you mail server is?