You should try starting one. You'd just need to work with every email provider on the planet (including people running personal email servers) and convince them to let you decide for them what is spam or not, get them to implement a massive list of IPs/domains to whitelist on their servers, get them to let you edit that list whenever new mass mailers sign up for your "We're totally not spam" service, and then get them to provide some way for complaints to come back to you so that you can enforce your rules. It'd be a hard sell for mail providers, and it wouldn't solve the spam problem for any messages that aren't sanctioned by your service.

If you can convince everyone to trust you, and your service, and that it'd be worth it for mail providers to do all that work on their end on top of everything they're doing currently to prevent spam, it really could improve deliverability.

You'd have to do a lot if work to validate new senders long before they send their first message and you start getting complaints or else you're just letting spammers pay you to completely bypass every mail provider's spam filters until they finally get blocked and have to create a new account with you under a different company name.

> You'd just need to work with every email provider

Why would you need to do that? Just work with those that'll pay you for it. The others won't care as they'll just ignore the header.

Would email providers pay for it at all? I suspect it'd be easier to take money from the would-be spammers than to get mail providers to do a bunch of extra work and then pay you for the privilege just so that your clients can send messages that look like spam a little easier.

I suppose that really you'd be able to get a lot of utility by convincing just a handful of very popular email providers (gmail) to trust that your service will never be used to send spam (or that they should let spammers who slip by you right past all of their spam filters). The more email providers you can get to use your service though the more you could charge the mass mailers for guaranteed message delivery.

Such a service could lead to two very bad outcomes though. Parents being told that if they want to get email from the school they'd better sign up for an email account at one of the few supported email providers (gmail) and/or (if it becomes successful) any sender who isn't paying for the privilege of sending email being treated like a spammer.

SMS has something similar to this. You have to honor requests to stop sending or are banned.

> I don't remember signing up for this

This is often not a non-sense complaint. A lot of newsletter signups are still via pre-selected checkboxes that are easy to miss.