The JetBackup Clone Job will automatically set the accounts Active to your Clone Server (Server 2) each time it runs. To disable services such as Mail from your Clone Server, please navigate to WHM > Service Configuration > Service Manager and select which services you would like to disable (email services such as Exim, Imap, and POP3 in your case). This will prevent emails from sending and receiving in Server 2.
Here are the following online resources regard disabling services in cPanel:
https://support.cpanel.net/hc/en-us/articles/1500005227942-How-to-disable-a-service-in-WHM-
https://forums.cpanel.net/threads/disable-mail-functions.606959/
If you have any other services/functions you would like to disable on your Clone Server, please reach out to your qualified server administrator or through cPanel for further assistance.
