Spamhaus Blacklisting for several /22 ongoing Thursday 18th February 2021 00:10:00


We currently have a Spamhaus SBL blacklisting for several /22 subnets ongoing, in total around 6k ip-addresses are affected. We are already in contact with Spamhaus to clarify whats going on. Most of the affected /22 even had almost zero abuse complaints in 2021 and were assigned to different customers. We currently suspect a bug or overreaction due to a few complaints for a single /24, which ended up in blacklisting those as collateral damage.

Spamhaus has delisted almost all our /22 prefixes, beside of one, which is exclusively allocated to one customer. We're going to tighten our anti abuse measures within the next couple of days.

The issue appears to be caused by a single prefix used by one of our customers for hosting hundreds of VPS. We have implemented measures and still wait for response from Spamhaus. Once the issue has been resolved, we will implement more strict proactive measures to block abuse. combahton does in general not tolerate any kind of illegal or shady activity. The incident affects quite a lot of legitimate customers, which arent even related to the abused prefix. It looks like Spamhaus just picked all prefixes which were affected in the past by single /32 SBL listings.