Once you got black-listed getting removed wasn't always an easy process no matter how quickly you tried fix whatever caused it.
I took a job in the year 2000, at a company with 3000 email users, listed by Spamhaus. First thing I did was close the open relay they were running. The listing was promptly removed, and the mail queue was back to normal within only a few days. I'm skeptical of your claim. I've never seen a confirmed case of Spamhaus aggression, but I've seen a lot that were disproven, and even more that sound like they were written by miscreants. Like the kind who would advocate DDoS attacks cough.
Open relays were at the time manageable, even the ones that suddenly appeared when someone installed an old OS-version, as were the process for getting removed from the blacklists due to open relays.
Once you had one a computer lab workstation hacked and used for spamming - not so easy to get whiteliested anymore.
The university had a class B-network, trying to get the staffs subnet whitelisted while keeping the computer-labs blacklisted was apparently not possible according to the spam clearing houses. Blocking port 25 for outgoing traffic not possible to check from the outside and didn't help.
I can understand that organizations like spamhaus are overworked don't have the resources to handle every non-standard case on the internet as quickly as the blocked ip-range would like, but the replies we got were truly unhelpful.
The fact that someone bothered to register the domain stophaus.com seems to indicate that my experiences isn't uniqueue.
I took a job in the year 2000, at a company with 3000 email users, listed by Spamhaus. First thing I did was close the open relay they were running. The listing was promptly removed, and the mail queue was back to normal within only a few days. I'm skeptical of your claim. I've never seen a confirmed case of Spamhaus aggression, but I've seen a lot that were disproven, and even more that sound like they were written by miscreants. Like the kind who would advocate DDoS attacks cough.