It had been augmented with complementary lists that include various other classes of hosts, allowing for customized email rejection by its users.
[4] SORBS adds IP ranges that belong to dialup modem pools, dynamically allocated wireless, and DSL connections as well as DHCP LAN ranges by using reverse DNS PTR records, WHOIS records, and sometimes by submission from the ISPs themselves.
Matthew Sullivan of SORBS proposed in an Internet Draft that generic reverse DNS addresses include purposing tokens such as static or dynamic, abbreviations thereof, and more.
[6] That naming scheme would have allowed end users to classify IP addresses without the need to rely on third party lists, such as the SORBS DUHL.
Generally it is considered more appropriate for ISPs to simply block outgoing traffic to port 25 if they wish to prevent users from sending email directly, rather than specifying it in the reverse DNS record for the IP.
[citation needed] SORBS has been accused of deliberately targeting innocent users through escalated listings.
SORBS produces and publishes daily statistics about its list to the otherwise defunct usenet newsgroup news.admin.net-abuse.bulletins (NANAB).