A computer-implemented method is disclosed. The method involves: providing to a first client computing device a first instance of a first software program that includes a first secret ID value; receiving a first account creation request that includes the first secret ID value; associating the first account creation request with the first client computing device; and approving the first account creation request and creating a first account for the first client computing device if less than a first threshold of previous account creation requests that include the first secret ID value have been previously received, and a presumption that the first client computing device is a spammer does not apply; or denying the first account creation request if either the number of previously received account creation requests that include the first secret ID value is equal to or greater than the first threshold, or the presumption that the first client computing device is a spammer applies.