After a cPanel server migration we came around a special situation where mail accounts are not listed in users cPanel. But if we check in the backend it exist.
First thing we have to do is to fix the mail box permissions.
# /scrips/mailperm
// This script will fix the mail permissions.
# /scripts/updateuserdomains
// This script will rebuild the domain information from backend data files.
If still the mail accounts are not listed in the cPanel we can do a upcp to fix this
# /scripts/upcp --force
While doing the upcp cPanel will rebuild the caches from the data files and mail accounts will be displayed in the cPanel.