Im not a pro with Centos or any linux version.

My previous control panel is plesk and the new one is Cpanel both running the same OS. We were forced to migrate because the server has crashed for 2 days and the company hosting us did not even try to provide support so we could continue our services which they have promised.

If i may ask will the listed steps work on a new host server but different ip with same linux version,domainname but different control panel?

1. Using FTP program login using sftp://yourdomain.com - username: root - password: (your root password)

2. Navigate to the folder /var/qmail/mailnames/yourdomain.com/emailname/Maildir/cur

3. Download to local drive

4. login to new server using SFTP and root credentials.

5. Upload

Would really appreciate any help i can get.

Probably not.
Qmail makes _no_ effort to be nice, compatible, convenient or friendly. Read extensively before you do anything. This is really a case where you want to have the new setup tested & working before you decommission the old one. About the best guide was http://www.lifewithqmail.org