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.
Got a specific error? See how to fix each problem.
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.
- DMARC
From p=none to p=reject: a staged DMARC rollout
A step-by-step plan for taking a client domain from DMARC p=none to p=reject, with exit criteria for each stage and what RFC 9989 changed about pct.
- DMARC
How to protect parked domains from spoofing
Domains that never send email are easy to spoof. Three DNS records lock them down: SPF -all, DMARC p=reject and a null MX. Copy them here.
- Domains
.uk domain renewals and expiry: what agencies need to know
What happens to a .uk domain after its expiry date, day by day: Nominet's 30-day suspension, the 90-day renewal limit, and how to never get there.
- Agencies
How to sell domain and email health to clients
For agencies and MSPs: how to open the conversation, what to put in the proposal, how to price it, and how the monthly report keeps clients paying.
- Deliverability
Google, Yahoo and Microsoft sender requirements explained
What Gmail, Yahoo and Outlook.com require from email senders: SPF, DKIM, DMARC, alignment, unsubscribe and spam rates, with the errors you'll see.
- DMARC
How to read a DMARC report
What a DMARC aggregate report contains, how to read each part of the XML, the four patterns you'll see, and what to do about each one.
- Agencies
Add domain and email health to your website care plan
What a website care plan usually misses, what to check each month, what to put in the client's report, and how to price the domain and email part.
- DMARC
NCSC Mail Check has closed: what small businesses and charities can use instead
NCSC Mail Check and Web Check closed on 31 March 2026. What that means for a small business or charity's email and website, and what to use instead.
Check a domain now
See how any domain scores on all nine checks, with the fix for each problem.