LT_POP3D = value

In the place of value if you replace with a number then the failed POP3 login attempt times per hour per account per IP address is greater than the IP gets blocked. Put the value to zero to disable the option. Please keep in mind that the IP is blocked temporarily and it automatically unblocks after an hour!

LT_IMAPD = value

CSF will check the value corresponding to the LT_IMAPD and compare it the number of IMAP login failure and if the failure count is greater than the value mentioned hen the IP will be blocked. Using a high number is recommended other than putting zero as (0=option as disabled). Since this is the temporary block for an hour after that the IP will be unblocked!