An address for an email activation isn't pulled from an arbitrary domain — it's issued from a pool the platform manages. Here's what that pool is, why you can't add your own domain to it, why the set of domains differs from site to site and shifts over time, and what that means when you place an order.
What the domain pool is, and why you can't add your own
The pool is a set of mail domains the platform runs: it maintains the receiving infrastructure, watches each domain's reputation, and hands out addresses from that set for specific orders. You don't pick a domain in isolation — you pick a ready pair, "site plus domain," that the system already keeps working for that combination.
That's exactly why an outside domain can't be connected: reputation, deliverability, and acceptance by the target site are the result of ongoing work on the domain from inside the platform, not a one-time DNS setup. A third-party domain would need to be warmed up and verified for every site from scratch, which defeats the point of instantly issuing a ready address.
Why different sites see different sets of domains
The same domain isn't guaranteed to work for every site. Each site filters incoming addresses at signup its own way, and what one accepts without issue another may reject outright. The platform tracks that match explicitly: for each site it offers only the domains confirmed to work for it, not one flat list handed out regardless of destination.
So the set for a marketplace and the set for a gaming platform almost never fully overlap, even if both domains sit in the same pool. The difference isn't domain quality — it's how that specific site reacts to it.
Why domain availability changes over time
Acceptance rules on the site side aren't fixed: a platform can tighten its filter and stop accepting a domain that worked fine yesterday. The moment that's detected, the domain drops out of the offering for that particular site — not out of the pool as a whole, just out of that one pair. For other sites where the domain still passes, it stays available unchanged.
This is normal behavior for a live pool, not a glitch: sites change policy without warning, and the platform reflects that as it happens rather than on a schedule. There's no way to predict the moment a pair gets dropped in advance — only to check its current state before you rely on it.
What this means in practice: check the pair before a batch, not after
Because availability shifts, the rule is simple: before launching a batch of signups on one site-plus-domain pair, confirm it with a single activation rather than trusting last week's result. A pair that worked seven days ago may already have dropped out of the offering for that site.
Checking after the fact costs more. If a pair has stopped being accepted and you only find out on the tenth order instead of the first, the cancelled activations refund the money but not the time spent waiting through each cycle.
Why price is tied to the pair, not the domain — and what to do if yours is missing
Catalog price applies to the site-plus-domain pair as a whole, not to the domain alone: it reflects both current availability and how reliably that specific combination passes with the target site. That's exactly why the same domain can cost differently depending on which site it's paired with.
If the domain you need isn't available for a given site right now, there are two working options: pick another domain from what's offered for that same site and verify it with one activation, or come back later — the set refreshes, and what was missing this morning can appear later in the day. For a walkthrough on picking a replacement without wasting test runs, see how to choose a mail domain for signup.
Frequently Asked Questions
Can I add my own mail domain to the pool?
No, the pool is entirely built and maintained by the platform. An outside domain can't be connected — only the set the system already keeps working for specific sites is available.
Why does a domain available for one site not show up for another?
Because sites filter addresses at signup differently. The platform offers each site only the domains confirmed to work for it, not one shared list handed out regardless of destination.
What should I do if a site-plus-domain pair disappears from the offering?
Pick another domain from what's available for that same site and verify it with a single activation, or wait — the set refreshes and the pair may come back later. Related reasons a domain can be rejected are covered in why sites block disposable mail domains.
If the address needs to survive an entire signup flow with repeat confirmations rather than a single email, the difference between a one-off activation and a rented mailbox is covered in temporary mail vs a rented mailbox. The current set of site-plus-domain pairs and their prices is in the email OTP section.