Email Sent Summary blank in WHM

You will need to check if the eximstats database is corrupt?

root@cpanel01 [~]# mysqlcheck eximstatseximstats.defers                                   OKeximstats.failureswarning  : Table is marked as crashedwarning  : 1 client is using or hasn't closed the table properlyerror    : Size of indexfile is: 286859264        Should be: 286861312error    : Corrupteximstats.sends                                    OKeximstats.smtp                                     OKroot@cpanel01 [~]#

In this case it was corrupted, so It needs to repaired through WHM >> Home »SQL Services »Repair a MySQL Database select eximstats and repair it