cpanel – Configuring the mail server after changing DNS

I have recently changed DNS name server so that one domain points to another hosting server. The website is doing well, but email has become a problem. Receiving an email works, but sending does not work.

I've deleted the MX record from the new web host and added 2 MX records that mapped it to the original.

What's the problem? Will it just have to wait 72 hours?

One thing I noticed is that the new server has a CNAME record of mail.domainname.com.