Spamhaus "zen" DNSBL has again listed our support ticket mailhost

Hi, For about the 5th time in the last 6 months, Spamhaus has listed the IPv6 address of our support ticket mail host as a spam source. I have checked every outbound port 25 connection from that host and verified that the only thing it sends is replies to support tickets. The previous times this happened I was able to de-list the host, but this time: https://www.spamhaus.org/query/ip/2600%253A3c03%253A%253A31%253A2000 just says "invalid input.", so I can't de-list it this time. Last time this happened I attempted to contact Spamhaus both by their web contact form and by twitter to ask for more info as to why they keep listing this host. I have not received a response. So, all I can conclude is that Spamhaus are wrong. Possibly someone is automatically reporting ticket responses to them as spam. I can only recommend not using their "zen" DNSBL for binary blocking decisions. If anyone has any contacts at Spamhaus that do actually respond then I would appreciate you putting me in touch. Cheers, Andy -- http://bitfolk.com/ -- No-nonsense VPS hosting