Does anyone have any experience with ivmSIP/24?
ivmSIP/24 is the invaluement /24 Sender’s IP DNSBL. Aka an “RBL”, this list includes those whole /24 blocks of IPs which only send spam. We recognize that the concept of /24 blacklists is not some amazing new idea we thought up. However, ivmSIP24 has two interesting distinctions:
Unlike most other /24 DNSBLs, ivmSIP/24 is attempting to have the same extremely low false positive level as ivmSIP. In contrast, other /24 DNSBLs will admit that they are aggressive to a point where blocking legitimate e-mail is almost a given if used for outright blocking instead of scoring.
Because all three invaluement DNSBLs are especially good at catching snowshoe spam, ivmSIP/24 is particularly useful for preemptively catching these same snowshoe spammers before a given IP is used to send spam the very first time. As a result, /24 blocks freshly allocated to snowshoe spammers will most likely get listed by ivmSIP/24 before getting listed by all other respected /24 DNSBLs.
I had not encountered them until today (a false positive on their part), although their website looks like it's from ~1998. The concept seems a bit flawed on first blush.