Greylists are murder on businesses that depend on receiving mail from new people.
I see SpamHaus as akin to a the Microsoft monopoly in the 90's. If your interests are aligned with them, great. And for most people they do a great job. But there a lots of small businesses who get caught up and nearly crushed. Because a listing on a blacklist can be murder for a business that depends on communicating with people over email.
Why are graylists that horrible? All it does is require the sending server to retry 5 minutes later; I don't see how that would have any impact on a business unless they are in the habit of being on the phone with new customers and asking them to send an email at the same time.
Assuming the sending server does that. Maybe it takes a few hours. Maybe it doesn't. Small businesses can be a mess, and you can't say "well, your customers suck" when the client complains about how greylisting is working for him.
Why in the world would greylists be "murder" on businesses? We use 10 minute greylisting, and I occasionally check the logs and it does not seem to ever cause us to lose e-mails from anything but spammers.
I see SpamHaus as akin to a the Microsoft monopoly in the 90's. If your interests are aligned with them, great. And for most people they do a great job. But there a lots of small businesses who get caught up and nearly crushed. Because a listing on a blacklist can be murder for a business that depends on communicating with people over email.