SPF lookup count and 10-lookup limit
CheckInbox calculates recursive SPF DNS lookups and flags configurations that exceed the 10-lookup limit, including a breakdown of include and redirect usage.
Email DNS checker
Check your email DNS before sending
Review SPF, DKIM, DMARC, MX and domain-level email configuration before launch. CheckInbox also detects SPF lookup-limit risks, duplicate records, DKIM selectors and problematic domain-role conflicts.
What CheckInbox DNS helps you verify
DNS Checker goes beyond simple record presence and highlights structural configuration risks that can affect email authentication and deliverability.
Duplicate SPF detection
Multiple SPF records on the same hostname are invalid. CheckInbox detects duplicate SPF records instead of simply showing them as separate TXT values.
DMARC configuration validation
Review missing or duplicate DMARC records, policy state, p=none monitoring mode, missing rua reporting and other configuration issues.
Real DKIM selector discovery
Check common provider selectors automatically, add custom selectors when needed, and show only DKIM records that are actually found.
Authoritative DNS fallback
If a default resolver returns incomplete SPF, TXT or MX visibility, CheckInbox can use authoritative DNS fallback to build a more reliable result.
Domain-role conflict detection
Detect risky CNAME and email-DNS combinations when one hostname is being reused across sending, tracking, landing-page, redirect or verification roles.
How to run a DNS check
Check the actual domain or subdomain used by your email infrastructure, not just the company root domain.
1
Enter the sending domain
Use the domain or subdomain that actually participates in email sending, authentication, return-path or related mail infrastructure.
2
Add a DKIM selector if needed
CheckInbox tests common provider selectors automatically. If your ESP uses a custom selector, add it before running the check.
3
Run the DNS check
CheckInbox reviews SPF, DKIM, DMARC, MX and relevant domain-context signals in one report.
4
Review Issue and Review states first
Prioritize SPF lookup overflow, duplicate records, missing or weak DMARC configuration, missing DKIM and other structural warnings.
5
Fix DNS and check again
After changing DNS records, allow time for propagation and rerun the check to confirm that the intended configuration is visible.
Recommended usage
- Check the real sending domain or subdomain instead of assuming the root company domain represents the full email setup.
- Rerun DNS Checker whenever you add a new ESP, CRM or marketing platform because each new SPF include can increase recursive DNS lookup usage.
- Do not create a second SPF record when adding another sender. Authorized services should be incorporated into one valid SPF policy.
- Do not remove a CNAME only because it is flagged for review. First confirm whether the hostname is intentionally used for tracking, redirects, landing pages or vendor verification.
Important to know
DNS Checker validates the visible DNS configuration of a domain, but correct SPF, DKIM, DMARC, and MX records do not guarantee inbox placement. Actual delivery also depends on the specific message, sender reputation, sending infrastructure, campaign volume, recipient engagement, and mailbox-provider filtering. Use DNS Checker to verify domain readiness, Scan to inspect a real email, and Check to measure actual placement.