Datev.de isn’t even an ISP it looks like a software firm to me – that provides software products for law firms, tax planners and such My guess is a local block on their mailserver for xs4all.nl for whatever reason. The only individual from there subscribed to the list – from searching the archives superficially so I could be wrong – is Andreas Schulze andreas.schulze at datev.de What xs4all is telling you is correct, there’s absolutely nothing they can do about some individual deciding to block whatever he wants on a mailserver that he controls. Large ISPs have users they are answerable to. IT firms on the other hand are shielded from their actual users (unless the users substantially outrank them) by “blocked due to corporate policies” – and such blocking can be surprisingly overbroad and with little or no redress, because the team that operates it does not consider a postmaster role all that necessary. --srs From: denis <ripedenis@yahoo.co.uk> Date: Monday, 20 February 2017 at 6:36 AM To: Suresh Ramasubramanian <ops.lists@gmail.com>, denis <ripedenis@xs4all.nl> Cc: <anti-abuse-wg@ripe.net> Subject: Re: [anti-abuse-wg] an ISP can't do anything? Hi Suresh I was replying to a message on the DB-WG and got this response: The message could not be delivered, the mail server at idvmailin04.datev.com [193.27.49.132] said: <<< 554 5.7.1 Service unavailable; Sender address [ripedenis@xs4all.nl] blocked using dbl.webradar.datev.de; gesperrt vom DATEV WebRadar, http://webradar.datev.de/lookup?domain=xs4all.nl, servertime=Feb 20 02:16:47, server=idvmailin04.datev.com, client=194.109.24.26 cheers denis On 20/02/2017 14:58, Suresh Ramasubramanian wrote: On 20-Feb-2017, at 2:22 AM, denis <ripedenis@xs4all.nl> wrote: It seems like XS4ALL is not able to do anything about being blacklisted. Obviously the message about handling abuse is not getting through.... It would help if you posted just what bounce and from where. XS4all has historically been quite proactive about abuse handling.