Mailbox provider · Onet Poczta
How to verify an onet.pl email address
Can you verify @onet.pl addresses?
YesYes. @onet.pl answers mailbox checks one address at a time.
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The checker opens an SMTP conversation with onet.pl's mail server, offers a random address first to rule out a catch-all, then names your address at RCPT TO and disconnects without sending. A rejection comes back invalid ("Mailbox not found") and an acceptance valid ("Mailbox exists"). Temporary replies come back risky. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
Mailbox existsMailbox not foundServer would not confirmOnet Poczta addresses can be verified without sending an email. On 12 October 2026 the onet.pl mail server mx.poczta.onet.pl rejected a made-up recipient at the SMTP RCPT TO step with 550 5.1.1 Recipient address rejected: User unknown, so a mailbox check can tell a missing onet.pl account from a real one.
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Live DNS snapshot: onet.pl
Checked 6 November 2026, 07:44 UTCRead from DNS at the time shown and refreshed at most once a day. MX says where mail for onet.pl goes; SPF and DMARC describe mail sent from it, not whether any one address exists.
- 1
mx.poczta.onet.pl
v=spf1 ip4:213.180.128.0/19 ip4:141.105.16.0/27 include:amazonses.com ip4:63.180.223.202 ip4:63.185.6.105 ip4:63.183.226.216 ip4:18.196.116.253 ip4:3.78.33.11 ip4:18.157.199.3 ip4:3.66.73.198 ip4:18.184.62.46 ip4:63.183.223.43 -allp=quarantine: meets the requirement and enforces it.
v=DMARC1; p=quarantine; sp=quarantine; rua=mailto:[email protected],mailto:[email protected]; ruf=mailto:[email protected],mailto:[email protected]Look up any other domain with the MX lookup or the email provider lookup.
Onet Poczta at a glance
| Operated by | Ringier Axel Springer Polska sp. z o.o., Warsaw, PolandSource: Onet Poczta terms (Polish, PDF) |
|---|---|
| MX hosts | mx.poczta.onet.plObserved 12 October 2026 (dig MX) |
| Answer to a made-up address | 550 5.1.1 Recipient address rejected: User unknown, returned at RCPT TOObserved 12 October 2026 (SMTP probe of a made-up recipient, no message sent) |
| Inactive accounts | On the free service Onet may end the service and delete the account with all its contents if the user has not logged in for at least 12 monthsSource: Onet Poczta terms (Polish, PDF) |
| Inactive accounts | Onet may let another user take a deleted address, but not before at least 12 months after the account was deleted, and some addresses may never be releasedSource: Onet Poczta terms (Polish, PDF) |
| Postmaster rules | Onet asks bulk senders to authenticate with SPF, DKIM, DMARC and BIMI, to send a List-Unsubscribe header and to use double opt-inSource: Onet Poczta help: recommendations for bulk senders (Polish) |
What Onet Poczta's server says about a missing mailbox
The reply that matters is the one to RCPT TO, the step where the checking server names the recipient. Onet Poczta answered our made-up onet.pl address with 550 5.1.1 Recipient address rejected: User unknown. A 5xx code at that step is a permanent "no such mailbox", which is the same answer a real message would get, so SimpleVerifier marks the address invalid with the reason "Mailbox not found". A 250 at the same step means the mailbox exists and comes back valid.
Before trusting a "valid", a careful verifier also offers a random address that cannot exist. Onet Poczta rejected ours, so onet.pl is not a catch-all: a 250 for your address is a real signal. Temporary 4xx replies (421, 450, 451) are about the connection, not the mailbox, and come back risky with "Server would not confirm" rather than invalid. Hard bounce vs soft bounce explains why that split matters.
Onet deletes free mailboxes after 12 months idle
Onet's terms let it delete a free account and everything in it after at least 12 months without a login. The same terms say the address can later go to another person, but only after at least 12 months, and some addresses may never be released. A @onet.pl contact who has been silent for over a year may have no mailbox at all.
Onet's advice for bulk senders asks for SPF, DKIM, DMARC and BIMI, a List-Unsubscribe header and double opt-in. Re-confirm older @onet.pl contacts and keep your own authentication in order.
Cleaning onet.pl addresses on a list
Because Onet Poczta answers honestly, onet.pl is one of the domains where verification removes bounces before they happen. Drop the invalid results, keep the valid ones, and re-check the risky ones later: a temporary reply on one day often turns into a clear answer the next.
A valid result only means the mailbox exists today. Addresses on an old consumer list go stale as people stop using them, so re-verify before each large send to an aged segment; how often to verify an email list gives a schedule. Upload the CSV to the verifier and download the valid, risky and invalid rows as separate files.
Common questions
- Can you verify @onet.pl addresses?
- Yes. @onet.pl answers mailbox checks one address at a time. The checker opens an SMTP conversation with onet.pl's mail server, offers a random address first to rule out a catch-all, then names your address at RCPT TO and disconnects without sending. A rejection comes back invalid ("Mailbox not found") and an acceptance valid ("Mailbox exists"). Temporary replies come back risky. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
- Can I check if an onet.pl address exists without emailing it?
- Yes. A verifier connects to Onet Poczta's mail server, names the address at the RCPT TO step and disconnects before sending. On 12 October 2026 the server rejected a made-up onet.pl address with "550 5.1.1 Recipient address rejected: User unknown", so a missing mailbox shows up as invalid and the owner receives nothing.
- What mail servers does onet.pl use?
- On 12 October 2026, onet.pl published these MX hosts: mx.poczta.onet.pl. You can look them up yourself with the free MX lookup tool.
- Why did an onet.pl address come back risky instead of invalid?
- Risky means the server didn't give a permanent answer during the check, usually a temporary 4xx reply or a timeout. It isn't proof the address is bad. Check it again later; Onet Poczta gave a clear rejection for a missing mailbox when we tested it.
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