TL;DR: Avoid using SpamHaus at all costs. They can blacklist without reason, they won't delist you.
Full: Avoid using SpamHaus at all costs. Here are the reasons why.
- Their listing policy states: SBL listings are immediate and, in the case of known spam operations, are preemptive. The SBL does not require warnings or have a 'grace period' and does not require physical evidence of spam received from any specific IP to qualify a listing (in the case of known spam gangs, any IPs under their control are listed on sight) (http://www.spamhaus.org/sbl/policy/)
Meaning they can blacklist anyone without any evidence. You might think this is a safety measure. But no, they indeed list IPs sometimes without a reason (check this WHT thread: http://www.webhostingtalk.com/showthread.php?t=396742)
- Their delist policy states only ISP could contact them. They don't have autodelist option. Not even enduser or provider not owning the IPs can contact them for delisting even if their IPs weren't noticed in sending spam.
To add more here (also noted on WHT thread above), they could list whole network segment, be it /24, /21 or whatever just because only a few adjacent spamming IPs were found within this block. They don't care that segment could be distributed among various providers, they don't care how RIPE/ARIN divides blocks there. It's just random thing depending on their mood.
Here is an example: http://www.spamhaus.org/sbl/query/SBL191352 They blacklisted /24 block from OVH only because there were 5 spams in 5 months. WTF!? 5 IPs spam once in a month and you blacklist the whole 254 hosts just because they have "similar looking IPs"!? Check inetnum below: inetnum: 37.59.151.0 - 37.59.151.31 It doesn't falls in any range. But SpamHaus doesn't care. Even "better", if you try to contact them to delist your IP, they just keep telling you what "only an ISP could do that". Yes means if you are a provider renting IPs from DC and there would be a few bad clients on your DC like once a month you might get yourself blacklisted for nothing. Imagine now you're a client of such provider renting a VPS there which runs your mail server. Now some domains won't accept mail from you if they use SpamHaus. You can't simply delist your static IP. You have to contact your VPS provider and in turn they can't delist as well. Now you are going through a chain where your VPS must contact their DC. This chain might be longer depending on the setup. You might end up waiting months in conversations. And even then it doesn't guarantees you a delist.
So please, avoid using them at all costs.