Domain Intelligence
Last Updated:
Post.cz
Safe to Send
Post.cz is operated by Seznam.cz. The domain runs 2 mail exchanges and SMTP is responsive, with 2 of 3 authentication standards in place.
Safe to Send
RISK
27
/100
Low
Verify Mailbox
Verify @post.cz emails
Live SMTP handshake against post.cz mail servers. No email is sent. 10 free per day, no signup.
Trusted by 400,000+ senders
4.9/5
From 8,500+ verified reviews
Reached out to support during our API integration last month. Response in under 15 minutes, the rep was so sharp and helpful that by the end of the thread it honestly felt like I was flirting with him. Amazing support team. A+++. Nathan Orozco · Lead Engineer · via X
SOC 2 Type II
GDPR
CCPA
99.7% Accuracy
Disposable
No
Persistent addresses, not throwaway
SMTP Live
Yes
Mail server responds to SMTP handshake
MX Records
2
Mail exchangers
Mail Exchange (MX) Records for post.cz Mail Exchange records. They tell other mail servers which hosts are responsible for receiving email at this domain, in priority order. Lower priority numbers are tried first.
#5
mx1.seznam.cz 77.75.77.90
Reachable
#10
mx2.seznam.cz 77.75.77.42
Reachable
SMTP Handshake
Simple Mail Transfer Protocol. We open a live SMTP connection to the primary MX and read the greeting banner. A response confirms the mail server is alive and accepting connections.
Responsive
BANNER220 email.seznam.cz ESMTP
Primary mail server accepted SMTP connection and returned a banner during the live audit.
post.cz Email Authentication SPF · DKIM · DMARC
SPF
Sender Policy Framework. A DNS record listing which servers are allowed to send mail for this domain. Receivers reject or flag mail from unauthorized servers.
Pass
TXTv=spf1 mx ip4:77.75.78.0/23 ip4:77.75.76.0/23 ip6:2a02:598::/32 ?all
Authorized senders are defined and pass SPF policy.
DKIM
DomainKeys Identified Mail. The sending server cryptographically signs outbound mail with a private key, and receivers verify the signature using a public key in DNS.
Missing
No DKIM signature detected on common selectors for post.cz.
No DKIM signature was detected. Receivers cannot verify the integrity of outbound mail.
DMARC
Domain-based Message Authentication, Reporting & Conformance. Tells receivers what to do when SPF or DKIM checks fail: none, quarantine, or reject.
None
TXTv=DMARC1; p=none; rua=mailto:abuse@seznam.cz; fo=d; ruf=mailto:abuse@seznam.cz
Monitoring only. Receivers take no action when SPF or DKIM fails.
post.cz Domain Registration WHOIS · Nameservers · Registrar
RegistrarREG-CZNIC
RegisteredSeptember 6, 1997
Last UpdatedSeptember 27, 2025
ExpiresOctober 28, 2026
Age28 years
TLD.cz
Authoritative Nameservers (2)
- ans.seznam.cz
- ams.seznam.cz
Registrant
Pavel Zima
Seznam.cz, a.s.
domeny-owner@firma.seznam.cz·Praha 5, CZECH REPUBLIC
Technical Contact
CZ.NIC, z.s.p.o.
CZ.NIC, z.s.p.o.
Praha 3, CZECH REPUBLIC
About this Domain
About post.cz
post.cz is a Czech email domain associated with Seznam.cz, the Czech Republic's largest internet portal. Based in Prague, Seznam provides free email through multiple domains including seznam.cz, email.cz, and post.cz for Czech users.
post.cz shares Seznam's authentication infrastructure with SPF and DKIM support. The service complies with EU GDPR and Czech data protection regulations.
The post.cz mail servers enforce recipient verification and reject invalid addresses. The domain does not function as catch-all. Rate limiting applies.
For delivery to post.cz, authenticate with SPF and DKIM. Follow the same practices as for seznam.cz. Comply with EU anti-spam regulations.
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Common Questions About post.cz
Is post.cz a disposable or temporary email provider?
No. post.cz is not a disposable email provider. It is classified as Free Email Provider operated by Seznam.cz and addresses on post.cz are persistent rather than throwaway. Mail sent to a valid post.cz mailbox reaches a real recipient.
How do I verify if a post.cz email address is valid?
The fastest way to verify a post.cz email address is to use our free email checker. Enter any @post.cz mailbox at the top of this page and our system performs a real-time SMTP handshake against post.cz's mail servers, confirming whether the mailbox exists, is reachable, and is safe to send to. No email is ever delivered during the check.
Can I check if a post.cz email exists without sending a message?
Yes. Our real-time email verification API connects directly to post.cz's mail server, opens an SMTP session, and queries the mailbox using the RCPT TO command without ever transmitting an actual email. The server's response confirms whether the post.cz mailbox is valid, full, or non-existent. The recipient never receives anything and never sees the check.
What are the MX records for post.cz?
post.cz currently publishes 2 mail exchange (MX) records. The primary MX is mx1.seznam.cz, which is the first server contacted when other mail systems try to deliver email to a post.cz address. The full list with priorities and IP addresses is in the MX Records panel above. MX records tell sending servers where to route email for post.cz.
Does post.cz use SPF, DKIM, and DMARC email authentication?
post.cz has 2 of the 3 standard email authentication records in place: SPF, and DMARC (policy: none). Adding the missing layer(s) would tighten anti-spoofing protection and improve deliverability for legitimate post.cz mail.
Why do emails to post.cz bounce or get blocked?
Bounces from post.cz usually fall into three buckets: the mailbox doesn't exist (5xx user unknown), the inbox is full, or your sending domain isn't authenticated to post.cz's satisfaction. The fastest fix is to run each address through a free email verifier before you send, and to make sure your own SPF, DKIM, and DMARC are configured correctly so post.cz's receivers trust you.
How can I verify a large list of post.cz email addresses?
Our bulk email verifier accepts CSV or TXT uploads with thousands or millions of post.cz addresses (or any mix of domains). Every address goes through 30+ checks including SMTP existence, post.cz catch-all detection, role-account detection, and disposable-domain matching. Results typically come back within minutes and previously-failed addresses on your blacklist are reprocessed for free. For continuous high-volume needs, see our unlimited email verification API.
Is it safe to accept signups from post.cz email addresses?
Yes, with normal hygiene. post.cz is a legitimate email service and signups from @post.cz behave like any other real user. Pipe each address through a real-time email verifier API at the moment of signup to catch typos and dead mailboxes, but there is no need to block post.cz by default.
What email format does post.cz use for usernames?
Most post.cz mailboxes follow common patterns like first.last@post.cz, firstinitiallast@post.cz, or first@post.cz, but the actual local-part rules depend on Seznam.cz. The only reliable way to confirm whether a specific @post.cz address exists is to run it through a free email verification tool. Guessing patterns will produce a high bounce rate and damage your sender reputation.
How is the post.cz risk score calculated?
The 0-to-100 risk score for post.cz combines disposable-domain classification, mail-server reachability, MX record presence and depth, SPF / DKIM / DMARC enforcement, DMARC policy strength, SMTP banner response, and domain age. Lower scores mean safer to send to. Disposable domains are pinned at the high end of the scale. The post.cz score is recomputed on every audit so it always reflects the live state of the domain.
Is post.cz a valid email domain?
Yes, post.cz is a valid free email domain operated by Seznam.cz. It provides permanent email accounts to users.
Is post.cz a disposable or temporary email provider?
No, post.cz is not a disposable or temporary email provider. It offers permanent email accounts with standard email features.
What mail server does post.cz use?
post.cz uses mail servers operated by Seznam.cz. Check the MX records section above for specific server details.
Can I send marketing emails to post.cz addresses?
Yes, with proper opt-in consent. Follow email best practices and ensure SPF, DKIM, and DMARC authentication is configured for your sending domain.
How do I verify an email address at post.cz?
Use BulkEmailChecker to verify post.cz addresses via SMTP checks. Verification behavior varies by provider. Our tool handles provider-specific rate limiting automatically.