While the number of SORBS blacklist entries have declined dramatically since last week, we are noticing an uptick in Non Delivery Reports (NDRs) from ISPs such as Verizon, Yahoo, SBC and Hotmail. In most cases, it appears that these ISPs’ latest netblocks (ranges of IP addresses that include recent spammers) are catching non-spamming companies in their nets, creating bouncebacks to them as well as to the actual spammers.
There have also been a fair number of FIVETEN family blacklist occurrences since Friday — identifying miscellaneous address blocks that have sent spam — which have also included non-spammers in their ranges.
And we are still seeing several reverse DNS issues (PTR records not pointing to the original IP address or missing “A” records), which can make it difficult to get de-listed when requested…and a few viruses identified by CBL. We’ll keep you updated on any changes to these current trends.