Typically, the biggest issue we see week-to-week involves non-spamming companies that have been caught in blacklist spam traps which block entire ranges of suspected spamming IP addresses. However, over the past few days several RBLs (including SORBS, SPAMCOP, PSBL, and even CBL) have listed many instances of spam being sent directly from the IP addresses of the companies that have contacted us with blacklist problems. Reports of ISP network abuse have also been noted by SPAMBAG, SPEWS and SPAM CANNIBAL.
As to Non Delivery Reports (NDRs) directly from ISP hosts, Earthlink has joined BellSouth and Comcast as the most dominant ones as of today. Otherwise, CBL and SPAMCOP have both listed infections from unknown viruses invading various companies’ networks…and reverse DNS issues have made a small resurgence. Have a great weekend!