Hostinger Email Email Verification

A domain hosted on Hostinger's mail platform publishes MX records pointing at Hostinger infrastructure, typically mx1.hostinger.com with a secondary host alongside it. The domain in the email address belongs to the customer, so you will not see the word Hostinger anywhere in the address itself. The MX chain is the only reliable tell, and it is how Mailthentic recognises the platform.

The SMTP conversation

Verification connects to the published MX host, greets it, declares a null sender, and issues RCPT TO for the address under test. The session is closed before DATA. No message is ever sent, and nothing lands in the recipient's mailbox.

What Hostinger's servers answer depends on how the individual domain was configured by its owner:

• If the domain has no catch-all and the mailbox does not exist, the server can return a 550. That is a definitive rejection: the mailbox is not there.
• If the domain has a catch-all enabled, the server returns a 250 acceptance for every address that is offered to it, real or not.
• Under load or when a probe pattern looks unusual, the server may defer with 421, 450, or 451. Those are temporary conditions, not failures, and Mailthentic retries with a backoff before deciding anything.

Why catch-all dominates on shared hosting

Shared hosting control panels make a catch-all trivially easy to turn on, and it is a natural choice for a small business that does not want to lose a message because a customer typed inof@ instead of info@. The result is that a large share of small-business domains on Hostinger, Namecheap, Bluehost, and other cPanel-style hosts accept everything at the SMTP layer. This is the single biggest reason a legitimate B2B list comes back with a pile of accept-all verdicts. It is not a defect in the list and it is not a defect in verification. It is the destination server declining to tell anyone which of its mailboxes are real.

Catch-all detection

Mailthentic does not assume. For each domain it probes with a random address that cannot plausibly exist, something no human would ever have been assigned. If the server accepts that control address, the domain is catch-all and is reported as accept-all. From that point on, no individual mailbox on the domain can be confirmed by SMTP, because the server will say yes to any address at all. Mailthentic will not describe such an address as valid, because that would be a claim the evidence does not support.

If the control address is rejected while the real address is accepted, the picture is entirely different. The server is discriminating between addresses, and the acceptance of the target address is a genuine signal that the mailbox exists.

What a result here actually means

A 550 on a Hostinger domain means the mailbox does not exist and the address should be suppressed. An acceptance on a domain that rejected the random control means the mailbox is real. An acceptance on a catch-all domain means only that the server accepts mail for the domain. Treating that third case as a confirmed mailbox is the mistake that puts bounces into an otherwise clean campaign, and it is why Mailthentic reports it as its own distinct verdict rather than folding it in with valid.