DNS
THE CERTIFICATE BEHIND THE CONNECTION

TLS certificate checker.

Inspect SSL/TLS certificates for any public domain or subdomain.

Checks HTTPS on port 443, including subject alternative names, validity dates and the presented chain.

SSL certificate

TLSv1.3

mx.postal.k.io · 185.199.221.125:443

Unverified
Certificate verification failed. These are unverified certificate details presented by the server. Peer certificate subjectAltName did not match expected name `mx.postal.k.io'

Certificate verification failed

Subject
CN=postal.k.io
Issuer
C=US O=Let's Encrypt CN=YR1
Valid from
2026-10-22T13:16:59+00:00
Expires
2027-01-20T13:16:58+00:00
Days remaining
80
Serial (hex)
066C9B3E46163EE187CA09C214653BC44AC8
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

DNS:postal.k.io

SHA-256 fingerprint

E7:A2:5F:1C:74:64:2C:C0:68:F6:3C:B4:DB:4F:38:83:60:6F:82:D6:AD:50:B1:9B:3B:AC:09:C1:40:04:26:E7
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
F6:C7:62:4E:33:B5:25:3F:54:15:C3:07:BF:90:66:8C:3F:EC:87:D0
authorityKeyIdentifier
1F:2F:35:BE:46:14:82:CD:40:B1:AE:79:2C:55:78:FA:F7:D4:68:FB
authorityInfoAccess
CA Issuers - URI:http://yr1.i.lencr.org/
subjectAltName
DNS:postal.k.io
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr1.c.lencr.org/73.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 00:1A:5D:1A:1C:2D:93:75:B6:48:55:78:F8:2F:71:A1: AE:6E:EF:39:7D:29:7C:8A:E3:15:7B:CA:DE:E1:A0:1E Timestamp : Oct 22 14:15:29.180 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:45:02:20:20:0B:24:D0:BD:46:50:A5:04:1A:A5:33: 93:1C:82:50:22:F9:27:B9:97:ED:BA:C8:91:D6:80:DB: 4D:79:2D:F3:02:21:00:DB:AC:07:74:11:4E:BB:F5:D2: 01:F2:33:33:50:89:3B:9B:47:9A:6D:26:3E:20:41:7E: F0:DE:FB:B3:BA:12:2A Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 44:E8:22:FC:2B:AB:0E:92:EE:D0:E9:FA:D6:96:64:60: 27:76:D0:17:60:E0:89:05:09:C9:23:A1:B0:3F:C3:7F Timestamp : Oct 22 14:15:26.232 2026 GMT Extensions: 00:00:05:00:0E:36:DE:D1 Signature : ecdsa-with-SHA256 30:45:02:21:00:8D:0B:BB:25:C8:4F:86:88:A7:E9:C4: FD:8E:C0:85:5F:AF:5B:E9:72:23:34:E8:CD:74:3F:77: A9:6D:C5:EB:B2:02:20:75:DC:02:E8:24:BE:76:0C:1D: 2F:AC:E3:56:5B:A1:6D:C9:1E:E6:16:FE:37:FB:25:8C: C6:BD:F1:43:CC:36:D2
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Cipher: TLS_AES_128_GCM_SHA256 · Checked 2026-11-01T00:46:50+00:00

Server-presented chain · 2 additional certificates

Chain certificate 1

Subject
C=US O=Let's Encrypt CN=YR1
Issuer
C=US O=ISRG CN=Root YR
Valid from
2025-09-03T00:00:00+00:00
Expires
2028-09-02T23:59:59+00:00
Days remaining
671
Serial (hex)
A20253F15F2691C05DC1CE13B9BCCA4E
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

13:94:96:34:D9:9C:D6:FD:6A:A8:0B:C0:34:FE:FA:CC:EB:19:69:FE:EF:98:65:86:71:3E:CD:BB:05:75:8D:3F
Certificate extensions & PEM
keyUsage
Digital Signature, Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE, pathlen:0
subjectKeyIdentifier
1F:2F:35:BE:46:14:82:CD:40:B1:AE:79:2C:55:78:FA:F7:D4:68:FB
authorityKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityInfoAccess
CA Issuers - URI:http://yr.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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=
-----END CERTIFICATE-----

Chain certificate 2

Subject
C=US O=ISRG CN=Root YR
Issuer
C=US O=Internet Security Research Group CN=ISRG Root X1
Valid from
2026-05-13T00:00:00+00:00
Expires
2032-09-02T23:59:59+00:00
Days remaining
2132
Serial (hex)
F24B6D17F9D9AD7CB1C9FEA78782699F
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

07:26:39:D0:B1:40:D5:BF:FA:E1:6A:D9:C3:F6:CC:60:86:04:06:21:F5:1E:E6:1A:6D:46:A8:91:5C:07:CF:76
Certificate extensions & PEM
keyUsage
Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE
subjectKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityKeyIdentifier
79:B4:59:E6:7B:B6:E5:E4:01:73:80:08:88:C8:1A:58:F6:E9:9B:6E
authorityInfoAccess
CA Issuers - URI:http://x1.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://x1.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

One endpoint on port 443. Server-presented chain; no revocation, OCSP, CT or full TLS security scan.

View certificate JSON

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