Hello List

Anyone from Bluewin reading?

We see a lot of seemingly legitimate traffic with envelope sender address in the domain bluewin.ch coming from hosts belonging to Bluewin (reverse DNS record is in domain bluewin.ch). However, these IP addresses are not listed in Bluewin's SPF record. As a result SPF check for sender domain bluewin.ch is not feasible.

Is there any particular reason why Bluewin does not list sending servers in the following IP ranges in their SPF record?

195.186.7.0/24 195.186.101.0/24 195.186.121.0/24 195.186.122.0/24 195.186.228.0/24 195.186.123.0/24 (partially listed in SPF record) 195.186.136.0/24 (partially listed in SPF record)

(this list is probably not complete...)

Best regards Lukas