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Authentication history · 59 days observed

slack.com

Observed from 4 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/slack.com runs.

  • 2fine
  • 2context

  • Looks fine

    present, ending -all

    Hard fail. The strictest setting and the right one once you are confident every sender is listed.

    v=spf1 include:_spf.qualtrics.com include:mail.zendesk.com include:_spfextra.slack.com -all

    See what this looks like →

  • Looks fine

    present with p=reject

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

    v=DMARC1;p=reject;fo=1:d:s;pct=100;rua=mailto:dmarc_agg@vali.email,mailto:0e5a5c34@inbox.ondmarc.com;ruf=mailto:0e5a5c34@inbox.ondmarc.com

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

  • Context

    No key found on the selectors we know

    This is inconclusive, not a failure. selectors cannot be listed from , so we probed the common ones for Klaviyo, Google, Microsoft, Mailchimp, SendGrid and Postmark. A custom selector will not show up here.

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

  • Context

    Receiving mail via Google Workspace

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

    alt1.aspmx.l.google.com, alt2.aspmx.l.google.com, aspmx.l.google.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 include:_spf.qualtrics.com include:mail.zendesk.com include:_spfextra.slack.com -all

    DMARC published.

    v=DMARC1;p=reject;fo=1:d:s;pct=100;rua=mailto:dmarc_agg@vali.email,mailto:0e5a5c34@inbox.ondmarc.com;ruf=mailto:0e5a5c34@inbox.ondmarc.com

    No DKIM key on the selectors we probe.

    MX records present.

    alt1.aspmx.l.google.com, alt2.aspmx.l.google.com, aspmx.l.google.com, aspmx2.googlemail.com, aspmx3.googlemail.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