Email activation through an API matters wherever a signup is confirmed by mail rather than by phone: mail clients, ad accounts without phone verification, forums, services where the code or link only arrives by letter. Here is how the mailbox request cycle works, what the common response codes mean, and how to poll status without hitting a request limit.
The email activation lifecycle: from request to code
The cycle has four steps. First, the client requests a mailbox for a specific site, and the system reserves a free address and returns an activation ID: the mailbox is now locked to that request, not handed to another client in parallel. Second, waiting for the letter, which the destination site sends to the assigned address — anywhere from seconds to a couple of minutes depending on the sender. Third, retrieving the code: once the letter arrives, the API returns the code or the link from it, depending on the confirmation format that site uses. Fourth, finishing the activation once the code has worked, or cancelling if the signup failed and the mailbox should be released early.
Why a mailbox only accepts letters from the sites listed at order time
When you order an email activation, you specify a site or a list of sites the mailbox should accept mail from. This is a deliberate sender filter, not a technical limitation: letters from sources outside that list are never parsed or surfaced through the API. One physical mailbox can serve several parallel requests for different services without letters getting mixed up between clients, and the filter keeps out spam and phishing mail that would otherwise clog the queue. If the site you are signing up on was left out of the list at order time, the letter simply never reaches the API output — the first thing worth checking when a code takes too long.
Common response codes and what they mean in practice
A "no mailboxes available" code means the address pool for a given site is temporarily exhausted: wait and retry in a minute or two, or target a neighbouring site in the same family if the service allows it. "Letter not received yet" is a normal intermediate state, not an error — polling again after a reasonable interval eventually returns the code. "Activation expired" appears when no letter arrives within the allotted window, keeping mailboxes from being tied up by forgotten requests; the address returns to the shared pool once it fires. "Cancellation accepted" confirms you closed the activation early yourself, which differs from expiry in that the client initiated it, not a system timeout. If the pool stays empty longer than usual, a support ticket asking about restocking beats retrying by hand.
Polling status without adding unnecessary load
A common way to break an integration is polling status in a tight loop, several times a second. That does not speed up delivery: speed is set by how fast the destination site sends the letter, not by how often you hit the API. A sane interval is once every few seconds, backing off further if the status stays unchanged — that cadence stays within the request limit and delivers the code no faster than tight polling would. The same principle applies elsewhere in the catalogue, for instance when configuring IP rotation via API: frequent polling burns through the limit without speeding up the result.
Email activation versus SMS activation in automation
In bulk-registration scenarios, email and SMS solve different problems and are usually used together. SMS activation is tied to a phone number: the code lands on a specific virtual line for the duration of the activation, priced by country and service — current directions are listed under SMS reception. Email activation is tied to a mailbox that can accept several letters from one or more listed sites over the rental period — a better fit where confirmation arrives with a delay, requires following a link instead of typing a code, or the service does not ask for a phone at all. A similar pattern runs through the order-and-renew cycle for proxy channels through the API. Signup automation is worth designing around both channels — they complement rather than compete.
Frequently Asked Questions
Can one mailbox be used for several sites at once?
Yes, if you listed several sites among the allowed senders at order time — the mailbox will accept mail from each of them within a single rental, without needing to order a separate address per service.
What if the code arrives but the site rejects it?
Check whether the code expired on the site's own side first — many services give it a short lifetime regardless of the API. If it is still fresh and still rejected, the letter was likely duplicated from another address, so check the whole letter rather than a trimmed fragment.
How do you tell the API is being polled too often?
Rate-limit codes show up instead of the expected activation status. If that happens repeatedly, widen the interval between polls, especially while waiting for the letter, when the state cannot change faster than the destination site can generate it.
The full set of methods, mailbox request parameters, and activation completion calls is covered in the technical API documentation.