How to Check a List of Seznam.cz Email Addresses at Once
For a Czech list, paste the addresses into the bulk Seznam email checker: it flags typos, duplicates and dead domains for everything, then asks Seznam's own server about the first 10. It counts seznam.cz, email.cz, post.cz and spoluzaci.cz as Seznam rows.
Seznam mailboxes don't last forever, so a Czech list ages faster than its owner expects.
What Seznam's server says
On 8 November 2026 those four domains all published mx1.seznam.cz and mx2.seznam.cz as their mail servers, and Seznam rejected made-up addresses at the recipient step on 12 October and again on 8 November. A result for a Seznam row therefore comes from Seznam.
Why mailboxes disappear
The Email.cz terms let Seznam block a mailbox that was never used in its first 14 days, or one its owner hasn't logged into for more than six months. Seznam also asks bulk senders for double opt-in and to delete non-existent and inactive contacts; see Seznam's sender requirements.
The by-hand way
- Filter your sheet to the four Seznam domains.
- Remove duplicates and spot typos.
- Test addresses one by one with the Seznam email checker.
Steps in the tool
Paste the list (other providers are marked as another provider), read the flagged rows, download the clean list, then let the first 10 go to Seznam's server for a live answer.
What this check cannot do
- Seznam doesn't publish how its servers answer mailbox checks; the handling is from our own checks, which can change.
- Typo-domain detection covers the big webmail domains and slips like .con, not Czech domain misspellings.
- A +tag repeat is marked as possibly the same inbox, not merged.
Next: the whole list
Use the verify page: the first 100 checks are free with a Google sign-in, no card.
Try it now
Paste your list into the bulk Seznam email checker.
Common questions
Can you check if Seznam addresses exist in bulk?
Yes. Seznam rejected made-up addresses at the recipient step on 12 October and again on 8 November 2026, so a Seznam row's result comes from Seznam's server. The free page asks about 10 live.
Are email.cz and post.cz Seznam addresses?
They use Seznam's mail servers: on 8 November 2026 email.cz, post.cz and spoluzaci.cz published the same mx1 and mx2.seznam.cz hosts as seznam.cz, and the tool counts all four as Seznam rows.
Does Seznam block inactive mailboxes?
The Email.cz terms allow Seznam to block a mailbox never used in its first 14 days, or one not logged into for more than six months.
How often should I re-check a Czech list?
At least twice a year, since valid means the mailbox exists today.
Is there a free bulk Seznam checker?
Yes. The whole-list pass is free, and a Google sign-in gives free checks for the rest.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.