Deliverability

Diagnose email DNS

Inspect a domain’s MX, SPF, DMARC, and DKIM records together to find why mail bounces or lands in spam.

When to use it

Use this when

  • Mail to or from a domain is bouncing, failing authentication, or landing in spam.
  • You are standing up a new sending domain and need SPF, DKIM, and DMARC in place.

Steps

Do this

  1. Run Mail healthOpen Mail health and enter the domain. dnsbin gathers the mail-relevant records in one pass.
  2. Read the parsed policiesSPF is parsed into includes and the all qualifier; DMARC shows the policy (none/quarantine/reject) and reporting addresses.
  3. Check DKIM selectorsdnsbin probes common DKIM selectors so you can confirm a public key is published. Add your provider’s own selectors in the DKIM selectors field (or the selectors query param) to probe them too.

Examples

Copyable commands

REST
curl 'https://dnsbin.ca/api/v1/mail?domain=example.com'
REST — custom DKIM selectors
curl 'https://dnsbin.ca/api/v1/mail?domain=example.com&selectors=s1,mandrill'

Operational notes

Keep in mind

  • A missing DMARC record or an SPF ending in +all is a deliverability red flag.
  • DKIM selectors are probed from a common list, so an absent key may simply use a custom selector — pass it via selectors (comma- or space-separated) to check it directly.