This indicates a buffer overflow vulnerability in University of Washington pop2d.
pop2d is a Post Office Protocol (POP) daemon. Due to inadequate input boundary checking, a remote user can execute arbitrary commands on a target system by passing it a specially-crafted FOLD command.
Any POP daemon that is based on University of Washington pop2d
An attacker can execute arbitrary command on a target system
Apply appropriate patches or upgrade the system to the latest non-vulnerable version.