Illingworth posts subdomain test, 1.26 vs 0.62 replies
One customer, 18 campaigns, and the man reporting the result also sells the inboxes.
Richard Illingworth has put numbers behind the subdomain build he earlier laid out as part of his domain rules. In an October test at one of his customers, inboxes sitting on subdomains returned 1.26 human replies per 100 emails against 0.62 from the same customer's regular Google inboxes, run on the same 18 campaigns over the same days. None of the subdomains ended up on a blacklist.
The build
The structure is one root domain carrying up to 20 subdomains, with 2 to 3 Google or Microsoft inboxes on each, so a single $10 domain supports up to 60 sending inboxes. Normally, Illingworth says, 60 inboxes means buying 20 separate domains. The rule he repeats is that the root never sends a single email. If one subdomain gets flagged you cut it off and the rest keep sending, but a flag on the root could, in his words, knock out all 60 inboxes at once.
Daily limits in the build are 10 cold and 20 warm-up emails per inbox, consistent with the 10 to 15 send ceiling he has published before. He frames the cost model as taking a $200 domain bill down to $10. He is packaging the whole thing as a free resource he calls The $10 Infrastructure Blueprint, handed out by DM to people who comment BLUEPRINT and follow him. The post also says the blueprint covers four situations where you should not use the setup, though he does not say in the post what those four are.
How much weight it carries
This is one customer, one month, one comparison. The method is better than most numbers posted in this niche, same campaigns and same dates rather than a before and after, which removes the usual excuse that copy or timing changed. But the split is still roughly double on a base of under 1.3 replies per 100, and the post does not say how many emails or inboxes were on each side of the test.
The other thing to hold in mind is who is counting. Illingworth says he and his business partners built Premium Inboxes, which sells configured inboxes to outbound teams, and the post ends with a link to it. That does not make the test wrong, but a vendor reporting a 2x result on its own product is a claim with a method attached, not a benchmark.
For people sending, the transferable part is not the 2x. It is the containment logic. Spreading 60 inboxes across subdomains of one root means a flag takes out a slice instead of a domain, provided you genuinely never send from the root.
on the same 18 campaigns and the same days, their subdomain inboxes got 1.26 human replies per 100 emails, against 0.62 from their Google inboxes.
send a single campaign from it, and one flag there COULD knock out all 60 inboxes at once.
Know what is landing before you burn another domain
One email a day. Under three minutes. What the operators found out yesterday.