SSL-Tools

SSL check results of ostad.app

NEW You can also bulk check multiple servers.

Discover if the mail servers for ostad.app 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 Sun, 19 Jul 2026 00:31:03 +0000

We can not guarantee a secure connection to the mailservers of ostad.app!

Please contact the operator of ostad.app and ask him or her to solve this problem. This result stays accessible under the following address:

/mailservers/ostad.app

Servers

Incoming Mails

These servers are responsible for incoming mails to @ostad.app addresses.

Hostname / IP address Priority STARTTLS Certificates Protocol
mx2.mxfilter.net
23.172.136.2
Results incomplete
10
supported
not checked
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
1 s
mx1.mxfilter.net
23.172.139.3
Results incomplete
10
supported
not checked
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
2 s
mx3.mxfilter.net
162.244.94.10
 20
supported
mta03.mxfilter.net
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
5 s
mx4.mxfilter.net
160.30.208.10
Results incomplete
20
supported
not checked
DANE
missing
PFS
supported
Heartbleed
not vulnerable
Weak ciphers
not found
  • TLSv1.2
  • SSLv3
3 s

Outgoing Mails

We have not received any emails from a @ostad.app address so far. Test mail delivery

Certificates

First seen at:

CN=mta03.mxfilter.net

Certificate chain
  • mta03.mxfilter.net
    • remaining
    • 2048 bit
    • sha256WithRSAEncryption
    • Hostname Mismatch
      • R12
        • remaining
        • 2048 bit
        • sha256WithRSAEncryption
          • ISRG Root X1 (Certificate is self-signed.)
            • remaining
            • 4096 bit
            • sha256WithRSAEncryption
Subject
Common Name (CN)
  • mta03.mxfilter.net
Alternative Names
  • mta03.mxfilter.net
Issuer
Country (C)
  • US
Organization (O)
  • Let's Encrypt
Common Name (CN)
  • R12
validity period
Not valid before
2026-05-14
Not valid after
2026-08-12
This certifcate has been verified for the following usages:
  • Digital Signature
  • Key Encipherment
  • TLS Web Server Authentication
Fingerprints
SHA256
CC:D4:C6:F8:D2:A3:EB:71:19:3F:B6:39:39:2C:F3:94:86:DC:D6:3A:02:17:9C:15:E5:A0:B2:93:90:8D:16:03
SHA1
28:E1:F7:53:3E:AD:8E:E9:C8:DB:E2:24:33:F2:F1:92:C1:FB:E4:37
X509v3 extensions
subjectKeyIdentifier
  • B4:99:06:5A:89:07:83:37:0F:EE:9F:A1:C2:B2:BF:E9:25:BF:3F:FA
authorityKeyIdentifier
  • keyid:00:B5:29:F2:2D:8E:6F:31:E8:9B:4C:AD:78:3E:FA:DC:E9:0C:D1:D2
authorityInfoAccess
  • CA Issuers - URI:http://r12.i.lencr.org/
certificatePolicies
  • Policy: 2.23.140.1.2.1
crlDistributionPoints
  • Full Name:
  • URI:http://r12.c.lencr.org/30.crl
ct_precert_scts
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : D7:6D:7D:10:D1:A7:F5:77:C2:C7:E9:5F:D7:00:BF:F9:
  • 82:C9:33:5A:65:E1:D0:B3:01:73:17:C0:C8:C5:69:77
  • Timestamp : May 14 16:25:05.049 2026 GMT
  • Extensions: none
  • Signature : ecdsa-with-SHA256
  • 30:46:02:21:00:F7:EA:66:0C:91:7F:44:4F:05:C8:20:
  • 58:A6:BD:2F:8F:6F:8E:B2:5B:F7:19:02:57:04:76:68:
  • 6E:CD:6E:B2:EC:02:21:00:ED:BC:EB:E9:E3:5A:21:19:
  • CB:4E:B4:2A:7B:F0:B2:37:9C:D9:A0:7C:EC:C9:F5:36:
  • 05:73:ED:D9:1A:C4:EA:62
  • Signed Certificate Timestamp:
  • Version : v1 (0x0)
  • Log ID : A8:26:CB:E3:0A:C6:35:12:46:53:3F:E0:65:F1:4F:19:
  • D9:6E:19:08:13:C4:1D:D9:6D:79:00:B3:12:3C:55:27
  • Timestamp : May 14 16:25:05.981 2026 GMT
  • Extensions: 00:00:05:00:0A:E3:A8:DC
  • Signature : ecdsa-with-SHA256
  • 30:46:02:21:00:B0:1A:F1:B7:2F:4F:BE:76:F2:AF:1B:
  • 2F:AA:54:1E:F6:40:7E:3C:7F:85:BE:9E:E8:4F:0B:74:
  • 5B:C1:A6:FE:52:02:21:00:95:F7:BE:97:82:8B:65:30:
  • 23:43:58:C8:02:46:1E:22:0C:09:C3:44:F2:B1:B7:7E:
  • 56:53:9F:BD:55:F6:21:8D