OP here: thanks for poking your head over the parapet. But we've submitted that form three times over five months, with no discernible effect. I have wondered

OP here: thanks for poking your head over the parapet. But we've submitted that form three times over five months, with no discernible effect. I have wondered if a pattern-matching algorithm is penalising us for having a similar IP address to a spammer. But given that practically all servers are now located at hosting companies, IP address is a completely valueless signal - and an arbitrarily damaging one. We have no control over other servers near us in IP space, and can't even ask our hosting company to deal with the spammer because we have no idea which IP address they are on. If you have access to an internal directory, could I prevail on you to pass this concern on to the Gmail spam filter team? I think there is a genuine bug here, and if they fix it and let me know, I promise to post a followup article saying that fixing this shows GMail isn't killing independant email on purpose.