only 6 domains link to every major email marketing tool

we have run this study twice now. the project management tools had 35 domains linking to all eight competitors. the website builders had 27. we expected email marketing tools to land somewhere in the same range. instead the overlap nearly disappeared: only six non-platform domains link to all eight. that collapse is not a failure of the method, it is the most useful thing the data told us.

how we pulled this

eight email tools: mailchimp, substack, brevo, mailerlite, kit, activecampaign, beehiiv, and buttondown. for each one we pulled its top referring domains ranked by cg_authority from the common crawl webgraph, then intersected the eight lists. here are the headline numbers (two of them are capped at 100,000 referring domains, so read those as "100,000 or more").

the overlap pyramid collapses

across the eight email tools there were 11,763 unique linking domains. the shape is still a pyramid, but a far steeper one than the previous two studies:

79 percent of linking domains link to only one of the eight tools, the steepest single-mention rate we have seen. the overlap that exists is still clean: among domains linking to four or more tools, 95 percent are real editorial domains and only 5 percent are platform noise. but the top of the pyramid almost vanished. only six non-platform domains link to all eight, versus 27 and 35 in the earlier studies.

the six domains that link to all eight

here is the entire thin top of the pyramid, the domains that link to every one of the eight email tools, by authority:

domains linking to ALL 8 email tools, by cg authority:

github.com          81
dev.to              62
webflow.io          62
buzzsprout.com      62
carrd.co            60
captivate.fm        56

Only 6 non-platform domains link to all eight.

notice what is not on this list: email media. there is no email-marketing trade publication, no deliverability blog, no newsletter-about-newsletters. the six universal linkers are cross-category infrastructure. developer platforms (github, dev.to), website builders (webflow.io, carrd.co), and podcast hosts (buzzsprout, captivate.fm). podcasters link out to the email tool they personally use, which is why a podcast host ends up linking to all eight. the category overlaps with podcasting and no-code, not with itself.

why the category is fragmented

the previous two studies worked because website builders and project management tools are real categories. people compare wordpress to wix, or asana to monday, and the same publications cover the whole field. "email marketing tools" is not one category, it is three or four wearing the same label.

someone choosing a newsletter platform compares substack to beehiiv to kit. someone buying marketing automation compares mailchimp to activecampaign to brevo. those are different buyers reading different sites, and almost nothing links to both worlds at once. when the buyers do not overlap, the backlinks do not overlap, and the all-eight list empties out.

how to do this for your own niche

here is the lesson, and it is the opposite of what you would expect. in a fragmented category, a whole-category gap analysis is nearly useless. running all eight email tools together gave you six domains, half of which were podcast hosts. the method did not fail, the input was too loose.

the fix is to define your true two or three competitors narrowly and run the gap on those alone. if you are a newsletter platform, compare yourself to substack, beehiiv, and kit, not to mailchimp and brevo. if you are an automation suite, do the reverse. the tighter the competitive set, the denser and more useful the overlap. the method matters more when the category is loose, because it is the only thing that tells you where the real boundaries are.

and the newcomer angle still holds inside each true category. buttondown has 2,928 referring domains against mailchimp and substack at more than 100,000. it does not need to match that volume, it needs the few hundred domains that link to indie newsletter tools as a habit. that gap is short and specific.

that is exactly what a backlink gap analysis does, and you can run it free on the same common crawl data we used here. enter your domain plus your true two or three competitors and you get the ranked, noise-filtered overlap in seconds. the free tier shows your top gaps; the lifetime plan unlocks the full list, csv export, and an api.