Domain and email health, explained plainly.
Practical guides for agencies and IT providers looking after other people's domains. No jargon without an explanation, and every guide ends with what to do next.
More guides
- SPF
SPF explained, and the 10-lookup limit
How SPF works, why records quietly break as clients add new services, and how to fix a record with too many DNS lookups.
- DKIM
DKIM explained: selectors, keys and rotation
How DKIM signing works, how to find a domain's selectors, why 1024-bit keys get flagged, and how to change keys without a gap.
- MTA-STS
MTA-STS and TLS-RPT for small businesses
How MTA-STS makes sure email to a domain arrives encrypted, how TLS-RPT reports problems, and how to switch both on safely.
Check a domain now
See how any domain scores on all nine checks, with the fix for each problem.