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Docs/Deliverability/How the infrastructure health score works

How the infrastructure health score works

Updated Apr 8, 2026 · 5 min read

The 0-100 score, what inputs it uses, how to improve it.

On this page · 3
  1. What goes into the score
  2. What drops a score
  3. How to improve a score

The health score is 0-100 per domain and per mailbox, refreshed daily. It exists because operators need a single number to triage from - not a scatter of separate signals to correlate manually.

What goes into the score

  • DNS authentication validity - 40% weight. The share of your domains with SPF, DKIM, DMARC and MX all passing.
  • DKIM verified at the mailbox provider - 40% weight. The share of mailboxes whose DKIM key is live at Google or Microsoft, not just published in DNS.
  • Blacklist status across the 6 domain blacklists - 20% weight. The share of checks that came back clean. Sources: Spamhaus DBL, SURBL, URIBL Black, URIBL Grey, Nordspam DBL, Invaluement URI.

    • What drops a score

    The score is a straight weighted average of the three inputs above, not a base score with penalties subtracted. Anything that lowers one input lowers the total in proportion to that input's weight.

  • A domain missing or failing SPF, DKIM, DMARC or MX pulls down the 40% authentication input.
  • A mailbox whose DKIM key is not yet live at the provider pulls down the 40% DKIM input. This is the usual reason a freshly provisioned domain scores below 100.
  • A blacklist listing pulls down the 20% blacklist input, in proportion to how many of your checks came back listed.

    • How to improve a score

    For DNS issues, click the offending row in the domain page and the dashboard shows the exact record problem and the proposed fix. Most DNS issues resolve in a single click - InboxLee re-publishes the record.

    For blacklist hits, the source determines the response. A Spamhaus DBL listing requires investigating the underlying sending pattern (volume spike, list-quality issue, compromised credential) before requesting delisting. The alert links to the delisting page for that source.

    For placement drops, pause sending for 48 hours, audit the most recent campaigns, and let reputation recover. Resume at half volume and ramp back up over a week.

    Below 70 is the action threshold. Above 85 is healthy. Between 70-85 is a watch zone.
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