Years ago, when I was at CREDO Action, I started a working group called the Progressive Deliverability Round Table. It was a loose network of email-program staff at progressive advocacy nonprofits who’d hop on a call every few weeks to compare notes on what was breaking — Gmail rules changing, Hotmail throttling, sender-reputation scares, the occasional spamtrap nightmare.

One of the artifacts of those calls was a shared exclusion list. Not formally maintained, not even consistently formatted — just a running document of email domains everyone agreed they should never be sending to. Typos like gmial.com, disposable services like mailinator.com, throwaway domains that bot-farms used to harvest action signups. Each org had its own version of this list, and the Round Table was where we compared.

CREDO Action wound down in early 2020. The Round Table went with it. So did the shared doc.

Why those lists exist

The basic problem hasn’t gone away. Real signups include real garbage: typos people type at 11pm on their phone, throwaway addresses generated by AI bots harvesting petitions, single-use disposables for free-swag offers that never convert to anything else. Send mail to those domains and your reputation with Gmail tanks. Do it long enough and your whole sending domain gets quietly throttled.

Most progressive nonprofits have figured this out the hard way. Many have some kind of internal list of domains they suppress at signup. And most of those lists are stuck in a Google Doc someone updated in 2019 that nobody’s brave enough to throw away.

This is wheel-reinventing on a quiet, costly scale. Days of work in some communications director’s calendar at every org, every couple of years, redoing what the comms director down the street already did.

What changed underneath

Meanwhile, an open-source ecosystem was building public lists of disposable email domains. I didn’t know about any of it until I went looking. disposable-email-domains/disposable-email-domains under CC0. FGRibreau/mailchecker under MIT, much larger. 7c/fakefilter under BSD. None of them progressive-specific. All of them covering most of the disposable-services problem any nonprofit faces.

If you had an engineering team, you could pull these into your stack and stop reinventing. If you didn’t (most progressive nonprofits don’t), they existed in a parallel universe you couldn’t easily reach.

So I assembled it

A few days ago I sat down and put it together: the two historical lists I had access to from the Round Table era, folded in with the three big public feeds. About 66,000 domains, deduplicated and normalized, rebuilt nightly:

jordankrueger/progressive-email-suppression

CC0-licensed. No attribution required. Use it however your mission needs.

For ActionKit users, most of whom don’t have engineering teams to spare, there’s a self-serve GitHub Actions workflow that bulk-imports the list straight into your AK instance’s Blackhole feature. Fork the repo, set three secrets, click Run workflow. About 10 minutes the first time you set it up. 30 seconds for refresh runs after that. Clear step-by-step instructions for non-technical admins, no code or technical expertise required.

There’s also a small allowlist of major email providers — Gmail, Outlook, Yahoo, iCloud, Proton, the big international ones — that gets stripped from every output file before publication. So even if an upstream community feed ever got vandalized and shipped gmail.com as a “bad” domain, you’d never end up suppressing your Gmail subscribers. Cheap insurance against a catastrophic mistake.

Why publish it CC0

The Round Table didn’t survive its parent organization. Neither did the shared doc. That’s the standard fate of organizational memory in nonprofit work: it walks out the door with the people who held it. Most of what I learned at CREDO would be inaccessible to me now if I hadn’t backed up a few key things personally.

This list is one of those things. The historical snapshots are in the repo, alongside the public feeds. Putting it all under CC0 means no one has to ask permission, no one has to track down an attribution, and no one has to wonder whether the next org-folding will take it with them. The list exists. Use it.

If you do, I’d love to hear about it.