Modify the Maximum Emails a Domain Can Send per Hour
On Cpanel’s Tweak Settings you can limit the maximum each domain can send out per hour. The problem is that this limit also applies to Mailman mailing list hence causing problem for mailing list owners.
The problem happen when the mailing list has members more than the maximum number of email a domain can send per hour. Once the mailing list hit the max limit, the emails start to be bounced back or dropped by Exim from its queue.
To fix this problem administrator can set a limit for a specific domain on the server by modifying /var/cpanel/maxemails file and add the domain that want its limit to be override:
domain.com=120 domain.net=500
Then run /scripts/build_maxemails_config to apply the new limit.
Changing /tmp Partition Size on CPanel Server
Today one of my server have its /tmp partition is full and causing problems such as failed MySQL database query or Fantastico stop working because they can't write temporary file. Here is the solution I found on CPanel's forum:
lsof /tmpThen umount /tmp and /var/tmp:
umount -l /tmp umount -l /var/tmp
Then remove the old partition file:
rm -fv /usr/tmpDSK
Then create a new one:
/scripts/securetmp
CPanel Problem Upgrading MySQL 5
Several months ago I had problem on upgrading CPanel's MySQL 4.1 to MySQL 5. The problem was occurred on Centos 5 OpenVZ based VPS. Since someone contact me at WebHostingTalk forum asking about the same problem so I decided to re-try again the steps to fix the problem. Hence I post it here too, for future and general purposes 
ok, do this at your own risk backup your mysql data first!
the steps i do: