SSL-Tools

SSL check results of posteo.de

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Discover if the mail servers for posteo.de 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 Wed, 22 Jul 2026 02:56:51 +0000

No connection to the mailservers of posteo.de could be established.

Servers

Incoming Mails

These servers are responsible for incoming mails to @posteo.de addresses.

Hostname / IP address Priority STARTTLS Certificates Protocol
mx02.posteo.de
185.67.36.73
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx03.posteo.de
185.67.36.70
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx03.posteo.de
185.67.36.63
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx04.posteo.de
185.67.36.71
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx04.posteo.de
185.67.36.64
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx01.posteo.de
185.67.36.62
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s
mx01.posteo.de
185.67.36.61
Results incomplete
10
supported
mx01.posteo.de
DANE
valid
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
7 s

Outgoing Mails

We have received emails from these servers with @posteo.de sender addresses. Test mail delivery

Host TLS Version & Cipher
mout01.posteo.de (185.67.36.65)
TLSv1.3 TLS_AES_256_GCM_SHA384
mout02.posteo.de (185.67.36.66)
TLSv1.3 TLS_AES_256_GCM_SHA384

Certificates

First seen at:

CN=mx01.posteo.de,O=Posteo e.K.,L=Berlin,C=DE,serialNumber=HRA 47592,businessCategory=Private Organization,jurisdictionL=Charlottenburg,jurisdictionST=Berlin,jurisdictionC=DE

Certificate chain
Subject
jurisdictionC
  • DE
jurisdictionST
  • Berlin
jurisdictionL
  • Charlottenburg
Business category
  • Private Organization
Serial number
  • HRA 47592
Country (C)
  • DE
Locality (L)
  • Berlin
Organization (O)
  • Posteo e.K.
Common Name (CN)
  • mx01.posteo.de
Alternative Names
  • mx01.posteo.de
  • mx02.posteo.de
  • mx03.posteo.de
  • mx04.posteo.de
  • mxv6.posteo.de
  • mxposteo01.muenster.de
  • mxposteo02.muenster.de
Issuer
Country (C)
  • US
Organization (O)
  • DigiCert Inc
Common Name (CN)
  • GeoTrust EV RSA CA G2
validity period
Not valid before
2026-04-17
Not valid after
2026-10-06
This certifcate has been verified for the following usages:
  • Digital Signature
  • Key Encipherment
  • TLS Web Server Authentication
Fingerprints
SHA256
F5:B8:CF:B9:A7:0D:6B:C9:EC:2A:B8:F6:BD:BA:F5:2A:50:52:C2:2A:60:D4:AA:2D:9D:14:24:C8:17:3D:FA:B1
SHA1
E0:13:78:E0:8B:6C:D7:90:09:C8:A7:2A:8F:DB:AC:31:37:15:2D:1B
X509v3 extensions
authorityKeyIdentifier
  • keyid:28:D2:CF:EE:09:84:75:DD:B5:B2:B5:BF:3C:D5:A0:C6:73:88:5D:1F
subjectKeyIdentifier
  • D8:28:32:D9:03:A7:98:85:CE:71:74:1C:75:CF:A1:4D:FB:83:FE:B9
certificatePolicies
  • Policy: 2.16.840.1.114412.2.1
  • Policy: 2.23.140.1.1
  • CPS: http://www.digicert.com/CPS
crlDistributionPoints
  • Full Name:
  • URI:http://crl3.digicert.com/GeoTrustEVRSACAG2.crl
  • Full Name:
  • URI:http://crl4.digicert.com/GeoTrustEVRSACAG2.crl
authorityInfoAccess
  • OCSP - URI:http://ocsp.digicert.com
  • CA Issuers - URI:http://cacerts.digicert.com/GeoTrustEVRSACAG2.crt
ct_precert_scts
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : C2:31:7E:57:45:19:A3:45:EE:7F:38:DE:B2:90:41:EB:
  • C7:C2:21:5A:22:BF:7F:D5:B5:AD:76:9A:D9:0E:52:CD
  • Timestamp : Apr 17 11:24:57.089 2026 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:44:02:20:3A:B7:55:A1:9F:B9:94:6A:D2:70:2E:D8:
  • D0:1D:54:11:98:54:6B:14:11:86:60:15:0F:07:84:04:
  • BA:AB:30:21:02:20:46:74:ED:5E:CB:D5:C3:F1:BD:DD:
  • B2:3E:08:5B:E7:BD:0A:BA:97:7C:E4:FE:E4:D7:72:DD:
  • 2C:7C:03:80:44:FC
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : D8:09:55:3B:94:4F:7A:FF:C8:16:19:6F:94:4F:85:AB:
  • B0:F8:FC:5E:87:55:26:0F:15:D1:2E:72:BB:45:4B:14
  • Timestamp : Apr 17 11:24:57.121 2026 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:44:02:20:10:AB:9D:CD:94:1F:56:C4:15:00:1B:63:
  • 01:92:85:0F:27:4D:9B:E6:10:32:2A:AB:68:4E:AD:6E:
  • 93:CB:E4:DC:02:20:5F:A1:E8:98:EF:5F:AB:8E:77:4B:
  • 6F:4E:99:5D:80:F4:1E:2C:90:C8:CD:CA:3D:FB:C1:86:
  • 47:61:CD:4F:06:90
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : 94:4E:43:87:FA:EC:C1:EF:81:F3:19:24:26:A8:18:65:
  • 01:C7:D3:5F:38:02:01:3F:72:67:7D:55:37:2E:19:D8
  • Timestamp : Apr 17 11:24:57.105 2026 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:46:02:21:00:F4:18:21:27:E6:32:B0:31:E8:72:C7:
  • E5:AE:74:FB:D2:25:7E:A3:09:53:B5:9B:C3:F3:16:C4:
  • 3B:45:08:04:C4:02:21:00:E0:D2:31:FB:4A:22:06:13:
  • CF:02:2E:85:9A:D8:1E:93:B0:D2:04:7C:07:86:C6:66:
  • CF:72:5B:0C:4E:96:6C:D6

DANE

DNS-based Authentication of Named Entities (DANE) is a protocol to allow X.509 certificates to be bound to DNS using TLSA records and DNSSEC.

Name Options DNSSEC Matches
_25._tcp.mx02.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx02.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx02.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
valid
_25._tcp.mx02.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx02.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx03.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx03.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx03.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx03.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx03.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
valid
_25._tcp.mx04.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx04.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
valid
_25._tcp.mx04.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx04.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx04.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx01.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
valid
_25._tcp.mx01.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx01.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx01.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—
_25._tcp.mx01.posteo.de
  • DANE-EE: Domain Issued Certificate
  • Use subject public key
  • SHA-256 Hash
valid
—