exim: /var/log/exim/mainlog /var/log/exim/paniclog /var/log/exim/processlog /var/log/exim/rejectlog (on FreeBSD, they have “exim_” in front of the filenames)
cPanel /var/log/cpanel*install* - These log files contain verbose logs of the cPanel installation, and should be the first point of reference for any issues which might occur ‘out of the box’ with new cPanel installations /usr/local/cpanel/logs/error_log - cPanel logs any error it incurs here. This should always be the first place you look when you encounter errors or strange behavior in cPanel/WHM. /usr/local/cpanel/logs/license_log - All license update attempts are logged here. If you run into any license errors when logging in, check here. /usr/local/cpanel/logs/stats_log - The stats daemon (cpanellogd) logs the output from all stats generators (Awstats, Webalizer, Analog) here. /usr/local/cpanel/logs/access_log - General information pertaining to cPanel requests is logged here (Client Information, Request /var/cpanel/updatelogs/update-[TIMESTAMP].log - Contains all output from each upcp. Named with the timestamp from which the upcp process was executed. /var/log/chkservd.log - The service monitoring daemon (chkservd) logs all service checks here. Failed services are represented with a [-], and active are represented with [+].
login_log - cPanel user login log melange.log - cPanel chat server log melange_msg.log - cPanel chat server message log
Apache /usr/local/apache/logs/error_log - All exceptions caught by httpd, along with standard error output from CGI applications are logged here. The first place you should look when httpd crashes, or you incur errors when accessing a website. /usr/local/apache/logs/suexec_log - Contains auditing information reported by suexec each time a CGI application is executed. If you receive an internal server error, with no relevant information being reported to the Apache error_log, check here for potential suexec policy violations. /usr/local/apache/domlogs/domain.com - The general access log for each domain configured with cPanel.
Exim /var/log/exim_mainlog ( Linux ), /var/log/exim/mainlog (FreeBSD) - Receives an entry every time a message is received or delivered /var/log/exim_rejectlog ( Linux ), /var/log/exim/rejectlog (FreeBSD) - Receives an entry every time a message is rejected based on either ACLs or other policies (for example, aliases configured to :fail /var/log/exim_paniclog ( Linux ), /var/log/exim/paniclog (FreeBSD) - Receives all entries exim doesn’t know how to handle. It’s generally a really bad thing when log entries are being written here, and they should be thoroughly investigated.
IMAP/POP/SpamAssassin
/var/log/maillog /var/log/messages
FTP
/var/log/messages - General information and login attempts are logged here. /var/log/xferlog - Is a symbolic link in most cases to /usr/local/apache/domlogs/ftpxferlog, which contains a history of the transactions made by FTP users.
MySQL
/var/lib/mysql/$(hostname).err - This path could vary, but is generally located in /var/lib/mysql. Could also be located at /var/log/mysqld.log
