SSL-Tools

SSL check results of smtp.o2isp.cz

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Discover if the mail servers for smtp.o2isp.cz can be reached through a secure connection.

To establish a secure connection a mail server has to offer STARTTLS (SSL), a trustworthy SSL certificate, support for the Diffie-Hellman-Algorithm to guarantee Perfect Forward Secrecy and must not be vulnerable against the Heartbleed attack. Futhermore we recommend using end-to-end encryption with GnuPG.

Summary

JSON Refresh

Report created Fri, 21 Nov 2025 10:28:16 +0000

The mailservers of smtp.o2isp.cz can be reached through a secure connection.

Servers

Incoming Mails

These servers are responsible for incoming mails to @smtp.o2isp.cz addresses.

Hostname / IP address Priority STARTTLS Certificates Protocol
smtp.o2isp.cz
90.176.151.100
 -
supported
smtp.iol.cz
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • TLSv1.1
  • TLSv1.0
  • SSLv3
1 s
smtp.o2isp.cz
2a00:1028:d:2963::108
 -
supported
smtp.iol.cz
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • TLSv1.1
  • TLSv1.0
  • SSLv3
1 s

Outgoing Mails

We have not received any emails from a @smtp.o2isp.cz address so far. Test mail delivery

Certificates

First seen at:

CN=smtp.iol.cz,O=O2 Czech Republic a.s.,L=Praha,C=CZ

Certificate chain
Subject
Country (C)
  • CZ
Locality (L)
  • Praha
Organization (O)
  • O2 Czech Republic a.s.
Common Name (CN)
  • smtp.iol.cz
Alternative Names
  • smtp.iol.cz
  • smtp.o2isp.cz
Issuer
Country (C)
  • US
Organization (O)
  • DigiCert Inc
Organizational Unit (OU)
  • www.digicert.com
Common Name (CN)
  • Thawte TLS RSA CA G1
validity period
Not valid before
2025-04-15
Not valid after
2026-04-14
This certifcate has been verified for the following usages:
  • Digital Signature
  • Key Encipherment
  • TLS Web Server Authentication
  • TLS Web Client Authentication
Fingerprints
SHA256
88:26:EA:83:D4:E6:50:85:26:09:8B:D9:78:FB:E0:65:AB:C2:F7:C3:AD:FD:86:F0:AB:43:1D:BD:BB:5A:C5:9C
SHA1
55:A5:D4:1E:69:78:1A:DE:86:A8:13:DB:8F:7E:7C:8F:FB:EF:47:DD
X509v3 extensions
authorityKeyIdentifier
  • keyid:A5:8C:FE:32:CC:EB:0F:2C:D4:19:C6:08:B8:00:24:88:5D:C3:C5:B7
subjectKeyIdentifier
  • 1A:13:E4:29:AD:87:2D:C2:DB:CC:A1:BE:B7:A6:FC:9A:76:C9:23:6D
certificatePolicies
  • Policy: 2.23.140.1.2.2
  • CPS: http://www.digicert.com/CPS
crlDistributionPoints
  • Full Name:
  • URI:http://cdp.thawte.com/ThawteTLSRSACAG1.crl
authorityInfoAccess
  • OCSP - URI:http://status.thawte.com
  • CA Issuers - URI:http://cacerts.thawte.com/ThawteTLSRSACAG1.crt
ct_precert_scts
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : 96:97:64:BF:55:58:97:AD:F7:43:87:68:37:08:42:77:
  • E9:F0:3A:D5:F6:A4:F3:36:6E:46:A4:3F:0F:CA:A9:C6
  • Timestamp : Apr 15 07:38:31.615 2025 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:45:02:20:0F:FB:E6:B4:E5:E6:4A:18:CA:FA:95:B2:
  • 35:24:25:D2:BE:A2:6A:E0:FE:03:2C:82:D0:DF:AE:4F:
  • 9B:FF:E4:6C:02:21:00:C8:32:87:08:55:88:11:B7:B7:
  • 6B:F0:DE:FF:32:21:07:B2:3A:39:97:31:1E:A5:67:39:
  • 0F:2C:02:16:02:78:6A
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : 64:11:C4:6C:A4:12:EC:A7:89:1C:A2:02:2E:00:BC:AB:
  • 4F:28:07:D4:1E:35:27:AB:EA:FE:D5:03:C9:7D:CD:F0
  • Timestamp : Apr 15 07:38:31.617 2025 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:45:02:21:00:AE:47:06:8B:52:2B:AC:8A:55:62:D2:
  • A4:86:D4:2D:A3:1D:94:57:E5:EF:5F:A1:FD:24:F6:16:
  • E1:88:46:EA:C8:02:20:42:D0:4D:FC:BF:AC:6F:19:1E:
  • 6C:72:7E:D7:E8:C6:E5:EE:6F:77:83:B7:FD:59:76:39:
  • E5:FD:F8:03:C7:2F:91
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : 49:9C:9B:69:DE:1D:7C:EC:FC:36:DE:CD:87:64:A6:B8:
  • 5B:AF:0A:87:80:19:D1:55:52:FB:E9:EB:29:DD:F8:C3
  • Timestamp : Apr 15 07:38:31.636 2025 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:45:02:20:5F:73:39:5B:73:B8:B1:3C:2C:3D:75:6D:
  • E1:03:AB:E0:CA:18:00:49:A2:44:77:84:32:3A:FD:F7:
  • 01:A3:15:72:02:21:00:B7:B5:6E:66:6B:51:03:FC:6C:
  • D7:D5:2B:2C:41:91:1B:D0:B4:55:B8:1D:92:A3:45:6E:
  • BB:A9:1F:F0:D6:CC:2E