Email domain tools
Free online checkers for the DNS records that decide whether your mail arrives. No sign-up and no cap on how many domains you check.
Email domain health check
All seven checks at once with a setup score from 0 to 100. The place to start.
SPF checker
Record syntax, the expanded include chain and a counter for the ten allowed DNS lookups.
DKIM checker
Key by selector, or a probe of two dozen known ones. Key type, length and revocation.
DMARC checker
Tag-by-tag policy breakdown plus verification that external report addresses are authorised.
MX lookup
Mail servers with priorities, their IP addresses and mail provider detection.
Why these records matter
Mailbox providers decide a message's fate before they look at its content. First they check whether the sending server is authorised to use your domain (SPF), whether the message was altered in transit (DKIM), and what to do when those checks fail (DMARC). An error in any one of them sends a campaign to spam no matter how good the copy is.
The awkward part is that these records break silently. Connect a new sending platform and you cross the ten DNS lookup limit in SPF. Switch mail providers and the old DKIM selector lingers while nobody publishes the new one. Configure DMARC with reports going to an address on another domain and the reports never arrive, because that domain never authorised them. In every case the DNS panel shows green ticks.
Where to start
If this is your first look at a domain, run the full email domain health check: it fires all seven checks at once and shows you where the gap is. The individual tools are more useful once you know what needs fixing and want the detail — for example, which include is eating your DNS lookup budget.