The default location for the mail log is /var/log/maillog on your VPS. By default, you will also have archived maillog files with the name of /var/log/maillog.1, /var/log/maillog.2, /var/log/maillog.3 and /var/log/maillog.4.
Finding specific text in a file can be faster if you look at these files in a shell prompt. Use a command like:
less /var/log/maillog
to view the file and search with the following key combination:
/searchtext
where "searchtext" is the actual text you are searching for. Hitting the '/' key and then hitting the Enter key while in search mode goes to the next instance of that text. Hitting the 'q' key will exit from less.
You can also search for specific text in a file. A command like:
cat /var/log/maillog |grep searchtext |less
will bring up a list of all lines with the string "searchtext" in the file /var/log/maillog and place that information in less.
For more information on cat, less, and grep use the "man" command. For instance, to find more information on the grep command type:
man grep
If you do not wish to log into a shell prompt you can also view files in the File Manager in the control panel. The File Manager will not open files if they become too large and does not allow you to search for text within the file.