Substack · Domain Security

Substack Domain Security

Domain security

Domain security posture for Substack, probed live across 2 host(s) and 1 registrable domain(s). 2 host(s) serve HTTPS (up to TLSv1.3); 2 advertise HSTS. Email/DNS controls: DNSSEC absent, SPF present, DMARC present (p=reject).

NewslettersPublishingCreator EconomySubscriptionsEmailPodcastingNotesMediaIndependent MediaPaid Content

Transport & Host Security

substack.com
HTTPS: yes · TLS: TLSv1.3 · HSTS: yes · cert expires: Aug 22 07:50:09 2026 GMT
support.substack.com
HTTPS: yes · TLS: TLSv1.3 · HSTS: yes · cert expires: Aug 16 23:44:59 2026 GMT

Domain (DNS/Email) Security

substack.com
DNSSEC: no · SPF: yes · DMARC: yes (p=reject) · CAA: none

Source

Domain Security

substack-domain-security.yml Raw ↑ 
generated: '2026-07-11'
method: probed
source: live DNS/TLS/HTTP probes of apis.yml + OpenAPI hosts
hosts:
- host: substack.com
  https: true
  tls_version: TLSv1.3
  cert_expires: Aug 22 07:50:09 2026 GMT
  hsts: true
  hsts_max_age: 31536000
- host: support.substack.com
  https: true
  tls_version: TLSv1.3
  cert_expires: Aug 16 23:44:59 2026 GMT
  hsts: true
  hsts_max_age: 259200
domains:
- domain: substack.com
  dnssec: false
  caa: []
  spf: true
  dmarc: true
  dmarc_policy: reject