SPF
Lists the servers allowed to send mail for your domain.
Without it: Anyone can send mail as you, and receiving servers trust your real mail less.
Free tools
Free domain security checkup
See why messages land in spam, get rejected, or can be spoofed. We read your SPF, DKIM, DMARC, MX, and nameservers, then show the fix for each. Free with an account.
Free with an account · results in seconds · no card. The domain you enter is shared with the NHM team so we can follow up if you'd like help. Stuck? Ask us.
Nameservers
SPF Records
DKIM Authentication
DMARC Policy
MX Records
What the checkup reads
Five records decide whether your email is trusted.
The checkup reads public DNS, the same records every receiving mail server reads before deciding what to do with your message. Nothing is installed and nothing on your domain changes.
DKIM
A signature that proves a message left your provider unaltered.
Without it: Providers cannot verify your mail is really yours, so more of it is filtered.
DMARC
Your instruction for mail that fails SPF or DKIM: reject it, quarantine it, or let it through.
Without it: Spoofed mail using your name is delivered, and you never hear about it.
MX records
Where mail sent to your domain is delivered. We recognize Microsoft 365 and Google Workspace and show the steps for the provider you actually use.
Without it: Mail to your domain bounces or goes to the wrong place.
Nameservers
Who answers DNS for your domain, which is where every fix above gets made.
Without it: You cannot change any record, and a DNS outage takes email and website down together.
Want the whole website checked?
The free IT checkup runs this plus HTTPS, security headers, exposed files, reputation, and registration.
Run the full checkupAfter the checkup
What a free account adds.
A free DomainGuard account
- The full record text and step-by-step fixes, written for the DNS provider you actually use
- Re-check after a DNS change, with results kept so you can see what moved
- One email address watched for dark-web breaches, re-checked on a schedule
- The same report in the DomainGuard iPhone app, with a push when a breach lists your email
On Starter and up
- DMARC reports: every service and server actually sending as your domain, legitimate or not
- Daily re-checks of your records without you asking, with an alert when one changes
- More monitored inboxes for the breach watch
DomainGuard for iPhone
Take the report with you.
Same account, same report. Add the domain you just checked and the next checkup is one tap. When a scan finishes or a breach lists your email, the app tells you.
- Requires
- iOS 16 or later, iPhone or iPad
- Cost
- Free, and the free plan is enough
- Account
- The same login as the web
- Today
- Installs through Apple TestFlight until the App Store release
Talk directly with the owner
Need help fixing email security issues?
Contact us today to learn how we can help you configure SPF, DKIM, and DMARC records to improve email authentication and reduce common deliverability problems.