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

smtp.si.com.pl · 185.254.64.29:443

Verified

Certificate chain, hostname and dates verified using this server’s CA store.

Subject
CN=mail.si.com.pl
Issuer
C=US O=Let's Encrypt CN=YR2
Valid from
2026-10-11T03:28:11+00:00
Expires
2027-01-09T03:28:10+00:00
Days remaining
66
Serial (hex)
068DABD57FF2C55E1D2A47EDFB397C92E54C
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

DNS:imap.si.com.pl, DNS:mail.si.com.pl, DNS:smtp.si.com.pl

SHA-256 fingerprint

D2:92:71:EB:1C:A9:7D:2B:38:80:C3:E8:27:81:53:06:8F:7E:57:E4:AE:97:F6:DF:56:28:E0:7B:BF:5A:7B:A0
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
21:34:03:DB:7E:4D:40:C2:E7:AE:27:B7:D0:40:7E:C1:7C:79:C7:E3
authorityKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
authorityInfoAccess
CA Issuers - URI:http://yr2.i.lencr.org/
subjectAltName
DNS:imap.si.com.pl, DNS:mail.si.com.pl, DNS:smtp.si.com.pl
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr2.c.lencr.org/77.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 59:6E:6C:33:86:94:B2:59:72:A2:56:C8:A0:E8:DD:90: 4A:76:E8:08:3D:DA:87:3B:01:08:38:28:14:3C:EE:59 Timestamp : Oct 11 04:26:41.953 2026 GMT Extensions: 00:00:05:00:0A:EE:BC:C1 Signature : ecdsa-with-SHA256 30:44:02:20:48:58:A3:0A:90:67:9D:B2:92:6C:27:98: 29:51:12:0B:F9:C5:FA:F2:A7:63:11:1D:B3:DC:62:C1: 96:14:F0:71:02:20:17:42:24:8A:5E:02:99:EB:96:E4: EB:00:72:7F:29:AD:D1:A1:64:0A:74:97:0E:00:51:82: BD:1C:C5:E4:85:C5 Signed Certificate Timestamp: Version : v1 (0x0) Log ID : D6:D5:8D:A9:D0:17:53:F3:6A:4A:A0:C7:57:49:02:AF: EB:C7:DC:2C:D3:8C:D9:F7:64:C8:0C:89:19:1E:9F:02 Timestamp : Oct 11 04:26:41.873 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:44:02:20:09:BC:36:2C:8A:B8:E4:85:A8:87:76:4A: AA:9E:B2:94:38:68:4F:85:20:03:80:7F:0E:ED:99:D1: F2:73:D6:AA:02:20:7E:82:BC:1D:8A:59:4C:A8:28:0E: 5A:F4:14:EE:27:DD:37:16:D7:49:49:85:8F:F7:13:0B: 3C:5D:63:0E:BA:58
-----BEGIN CERTIFICATE-----
MIIGFDCCBPygAwIBAgISBo2r1X/yxV4dKkft+zl8kuVMMA0GCSqGSIb3DQEBCwUA
MDMxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MQwwCgYDVQQD
EwNZUjIwHhcNMjYxMDExMDMyODExWhcNMjcwMTA5MDMyODEwWjAZMRcwFQYDVQQD
Ew5tYWlsLnNpLmNvbS5wbDCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIB
AMAWdJ7Sx6C+CxR/PhyyQ+GbvFE8jXpDOOJVCKeusEX7ztzlsDrCo4fShihMBj8i
+dE/UDbQqowm6s1K18Bwp/M4b3EI+Ltb7b9rCaVreQ1ruxqiTUHH76eISzWmN/i1
SLAIte/i37D5ZK+HwVtdeWv3yBw5SrX4LNohn5KE+suU7TKMZvtglYAF8V17NaUM
Dt3xHYZMzog9lybZNn01eNWWbCDI57Tq3bg3OKPqujf90DvvAo1wglLYUozrxnhp
yCEGwkjgzC9XKxwtQpeG+0JMq6RVXxXPJrRY/QSHXMNfoYgsdzOtL/PvKi8eIICc
Ghv+iDOBmOkkEWVZ3xm1Aqp+pe5AooK3bbEGnuLk5a1a6aZp0j4nHYO5u8hKcxwm
+8x6KXoV2Buclfm/iZxv0+d7DievzDmFJcf7e+uWfwsORkbcB2CeJzvGPRMsMLIZ
KXkFzPnoKiHxnRhJVMSLQ1LLSJnIU1p2blv1x6UcBCM664yRUDKdJ2C7BhuLiff/
dTjGoaEYu0BvqQsi7jQKYn53Y5zn1Oq8/LRVUUtVcXgVf1VQTTJvpDvLfFUEqoLT
oremnBTe5S5/XiPd+uwbMw0MMwl7XZnR2jXQr1i0rJxm2OmZODuF1r+k4onKdhpa
rNUn2dl5NSoH5z6d5ZGtDlVk8qsHfRvbH2TJbDx4flsTAgMBAAGjggI6MIICNjAO
BgNVHQ8BAf8EBAMCBaAwEwYDVR0lBAwwCgYIKwYBBQUHAwEwDAYDVR0TAQH/BAIw
ADAdBgNVHQ4EFgQUITQD235NQMLnrie30EB+wXx5x+MwHwYDVR0jBBgwFoAUQBUt
JnntMiCe35pyHdYyH4EMgQwwMwYIKwYBBQUHAQEEJzAlMCMGCCsGAQUFBzAChhdo
dHRwOi8veXIyLmkubGVuY3Iub3JnLzA5BgNVHREEMjAwgg5pbWFwLnNpLmNvbS5w
bIIObWFpbC5zaS5jb20ucGyCDnNtdHAuc2kuY29tLnBsMBMGA1UdIAQMMAowCAYG
Z4EMAQIBMC4GA1UdHwQnMCUwI6AhoB+GHWh0dHA6Ly95cjIuYy5sZW5jci5vcmcv
NzcuY3JsMIIBCgYKKwYBBAHWeQIEAgSB+wSB+AD2AH0AWW5sM4aUsllyolbIoOjd
kEp26Ag92oc7AQg4KBQ87lkAAAGhKTaHoQAIAAAFAAruvMEEAwBGMEQCIEhYowqQ
Z52ykmwnmClREgv5xfryp2MRHbPcYsGWFPBxAiAXQiSKXgKZ65bk6wByfymt0aFk
CnSXDgBRgr0cxeSFxQB1ANbVjanQF1Pzakqgx1dJAq/rx9ws04zZ92TIDIkZHp8C
AAABoSk2h1EAAAQDAEYwRAIgCbw2LIq45IWoh3ZKqp6ylDhoT4UgA4B/Du2Z0fJz
1qoCIH6CvB2KWUyoKA5a9BTuJ903FtdJSYWP9xMLPF1jDrpYMA0GCSqGSIb3DQEB
CwUAA4IBAQCmrLNUWV06RkQrQRwbfv5A2/zQtWgewGK71Ga9UGnGJv+9LW+EX4OX
RUlsDGrz3NIZTyMsjTx2QrBKJ6IsI3RljBC2OqKfFmJZPIg84f0peWiuusC9tszH
r0zrbhd4VSPYthwO2OuqgUL9TEuvYYmkiNc6KMXGuj6r9JhsvDyjJN5cGHqtFSCd
wtfVROE6avqZFUbkLLo51GVwP1aW0/Tv0YgunUl1uMIrcE87FxMgwngA3N3uoDK8
v51KfVqEz3UJ9OeccK8hCWCaN2Idj/Kq7CVkSoQm2OB8qXplDVNGHttQy/1QXl6F
8I53tt/qAuN3j6Uv60hOPOD8S7cTEsge
-----END CERTIFICATE-----

Cipher: TLS_AES_128_GCM_SHA256 · Checked 2026-11-03T20:04:23+00:00

Server-presented chain · 2 additional certificates

Chain certificate 1

Subject
C=US O=Let's Encrypt CN=YR2
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
669
Serial (hex)
4EBD24947E24D394802D84A52FD5B319
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

23:8B:85:A0:09:9C:65:B9:70:47:7D:57:24:F1:A1:D4:75:CE:50:58:CF:FE:4E:FA:87:33:89:9B:DB:86:3C:47
Certificate extensions & PEM
keyUsage
Digital Signature, Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE, pathlen:0
subjectKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
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
2130
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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