SPF, DKIM & DMARC Inspector
Check your domain's email authentication records before sending outbound email. This free DNS checker inspects SPF, DKIM, and DMARC configuration to help you identify common authentication and deliverability issues.
What Does This Email Authentication Checker Check?
Your domain's DNS records play an important role in email authentication. SPF, DKIM, and DMARC each solve a distinct part of the deliverability chain.
Sender Policy Framework (SPF)
Tells receiving mail servers which IP addresses and systems are authorized to send email on behalf of your domain, highlighting missing records and lookup limit violations.
DomainKeys Identified Mail (DKIM)
Adds a cryptographic digital signature to outgoing messages. Receiving servers use the public key published in DNS to confirm content wasn't altered in transit.
DMARC Policy & Alignment
Defines policy handling (none, quarantine, or reject) for messages that fail SPF or DKIM alignment, giving domain owners visibility and reporting control over unauthenticated mail.
SPF, DKIM & DMARC Are Not the Same Thing
| Protocol | Main Purpose | Failure Outcome |
|---|---|---|
| SPF | Identifies authorized sending server IPs and mail sources | Softfail/Fail flag on message headers |
| DKIM | Uses a cryptographic signature to verify sender origin and content integrity | Signature verification error / Header discard |
| DMARC | Defines policy alignment rules and reporting instructions for failed messages | Quarantined to spambox or rejected entirely |
Frequent Authentication Errors
- Missing SPF Record: Receiving servers cannot confirm if your SMTP host is permitted to send.
- 10-Lookup SPF Limit: Multiple nested includes cause SPF lookups to breach DNS query limits.
- Missing DKIM Selector: Public cryptographic keys are missing or mapped to invalid subdomains.
- Outdated DNS Records: Changing email infrastructure without updating live records breaks alignment.
Pre-Campaign Checklist
- [OK] Validate SPF syntax and lookups
- [OK] Verify public DKIM key selectors
- [OK] Publish explicit DMARC alignment policies
- [OK] Run pre-send list hygiene and verification
- [OK] Establish steady volume pacing and warmup
DNS & Authentication FAQ
What is an SPF checker?
An SPF checker queries the TXT records published on your domain and checks whether authorized IP addresses, includes, and syntax comply with email RFC standards.
What is a DKIM checker?
A DKIM checker verifies that your domain's public key record is published and properly formatted at the expected selector location.
What is a DMARC checker?
A DMARC checker inspects the `_dmarc` subdomain record to verify that policy tags (p=none, quarantine, or reject) and aggregate reporting addresses (rua) are correctly specified.
Does a good authentication score guarantee inbox placement?
No. Authentication gives receiving mail filters proof of identity, but inbox placement also depends on list bounce rates, recipient engagement, copy relevance, and mailbox reputation.
How often should I check my DNS records?
Run a check whenever setting up new mailboxes, changing email hosts, or modifying DNS entries to ensure records didn't get overwritten.
Scale Your Sending Infrastructure
Connect multiple authenticated domains, automate peer-to-peer mailbox warmup, and launch multi-mailbox outbound campaigns from one dashboard.