Um, Pat -- that's not correct. The ISP has absolutely nothing to do with your domain name. You don't tell him what you want to be known as at all in most cases. Usually they just assign you an IP address. If you have your own AS number and assigned block and are going to run BGP, you tell them what your IP is. But in either case, no domain names are involved. The only time the ISP might nbeed to know that info is if in addition to being your ISP they are also providing additional value added services, above and beyond just being an ISP, such as DNS hosting or SMTP mail.
The registrar is the only business that needs to know about your domain name. Our ISP does not know/need to know/care what our domain name is.
Given that in most cases involving spammers, the ISP has no way of knowing what registered domains are using a block of addresses, that won't work.
There is such a system in place more or less. The ROKSO list run by spamhaus is pretty much what you describe.
It's of limited use, however. The spammers use prepaid debit cards under phoney names to register domains, so they can't be identified before hand by the registrar.
Most spammers these days don't even really have an internet connection for their business per se -- they hire a sleazy overseas company to host their server for them. They use fake names again to do this. The spam is sent as follows -- somone gets a consumer level dsl, dial up, or cable internet account. They then use this ISP connection to get trojan infected PC's worldwide to send the spam for them. Since no spam comes form their own account, it never gets traced to that account. The only identifiable things are the domain name of the server, the registrar of the domain name, and the company hosting the server.
[TELECOM Digest Editor's Note: Seems like an awfully convoluted way of running your business, IMO. So my response would be to kill the domain name of the server, chop off the registrar's head, and burn down the company hosting the server. Fair enough? As one writer here yesterday pointed out, the ISPs could cure a huge amount of the problem (but I would say give the registrars some part of the job also) if they gave a Good God Damn, which many of them do not, such as MCI. And don't forget, MCI uses their employee Vint Cerf as their front man/mouthpiece with ICANN, truly God's Gift to Netters everywhere.And the small business people who run local ISP operations who _do_ care and _do_ attempt to check out new customers are treated like imbiciles, the same as your Esteemed Moderator. PAT]