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Authentication history · 61 days observed

github.com

Observed from 3 Aug 2026 to 3 Oct 2026. Nothing published in DNS has moved in that window.

Where it stands today

Live lookup, 3 Oct 2026. The same check /check/github.com runs.

  • 3fine
  • 1context

  • Looks fine

    present, ending ~all

    Soft fail. Accepted everywhere, though -all is stronger once your sender list is complete.

    v=spf1 ip4:192.30.252.0/22 include:spf.protection.outlook.com include:_netblocks.google.com include:_netblocks2.google.com include:mail.zendesk.com include:_spf.salesforce.com include:servers.mcsv.net include:mktomail.com include:sendgrid.net ip4:62.253.227.114 ip4:166.78.69.169 ip4:166.78.69.170 ip4:166.78.71.131 ~all

    See what this looks like →

  • Looks fine

    present with p=quarantine

    A policy that actually instructs receivers, which is more than most senders publish.

    v=DMARC1; p=quarantine; sp=reject; pct=100; rua=mailto:dmarc@github.com; ruf=mailto:dmarc@github.com; fo=1

    From DMARC p=none is monitoring, not enforcementSee what this looks like →

  • Looks fine

    keys published on 6 selectors

    A key existing is not the same as working. Read a real received header and check the d= value matches your before you call this done.

    google._domainkey (Google Workspace), k1._domainkey (Mailchimp), k2._domainkey (Mailchimp), selector1._domainkey (Microsoft 365), s1._domainkey (SendGrid), s2._domainkey (SendGrid)

    From DKIM passing is not DKIM alignedSee what this looks like →

    Part platform, part you

    The key is Mailchimp's to publish and it has. Whether it signs the domain in your is yours to confirm, and cannot show it — send one campaign to yourself and look for =pass header.d=github.com in the Authentication-Results header.

  • Context

    Receiving mail via Microsoft 365

    Where you receive mail says nothing about where you send it. Marketing sends usually leave through a different platform entirely.

    github-com.mail.protection.outlook.com

    See what this looks like →

What has moved

One entry per day a published record actually changed. Days we looked and found nothing different are counted, not listed.

  1. First observation — what was already published

    SPF published.

    v=spf1 ip4:192.30.252.0/22 include:spf.protection.outlook.com include:_netblocks.google.com include:_netblocks2.google.com include:mail.zendesk.com include:_spf.salesforce.com include:servers.mcsv.net include:mktomail.com include:sendgrid.net ip4:62.253.227.114 ip4:166.78.69.169 ip4:166.78.69.170 ip4:166.78.71.131 ~all

    DMARC published.

    v=DMARC1; p=quarantine; sp=reject; pct=100; rua=mailto:dmarc@github.com; ruf=mailto:dmarc@github.com; fo=1

    DKIM keys on selectors we probe.

    google._domainkey (Google Workspace), k1._domainkey (Mailchimp), k2._domainkey (Mailchimp), s1._domainkey (SendGrid), s2._domainkey (SendGrid), selector1._domainkey (Microsoft 365)

    MX records present.

    github-com.mail.protection.outlook.com
Where this comes from. Public DNS, and nothing else. We read the same TXT and MX records any mail server reads before accepting a message, on the days someone looked. There is no scan, no login, no mail, and no score here — only what was published and the date we saw it. Gaps are days we did not get a clean answer from a resolver, and we would rather leave those blank than guess at them.
Run the full checkSee which rules are yours