The default databases that are automatically generated on the WHM/cPanel server are
cphulkd: This is the default database of WHM/cPanel that stores the information log from the cpHulk software utility of your server. In common, the cpHulk utility is used for the protection purpose to prevent the server from potential attacks and brute force login attempts.
eximstats: This database allows to find more detailed errors regarding email. This database consists of tables which cover the information about mail failures, sends, and SMTP.