No email service after upgrade to cPanel 112

Hello community, we upgraded our servers to AlmaLinux 8.7 and cPanel 112. (then migrated all accounts from cPanel server with older version and CentOS) Now there are many fatal issues. One issue is that the mail accounts do not work. We nor can send emails neither receive mails. We can't find any solution, but read that the used Exim service has incopatibilities. What can we do? (really important...) Thank you, regards, Thomas