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Email & Deliverability

SPF Checker

Validate a domain's SPF record and see its DKIM, DMARC, and MX setup alongside it.

Domain

Check a domain's SPF, DKIM, DMARC, and MX setup for email spoofing protection.

Catch SPF breakage before bounces start.
SYNAPSE watches your SPF and the rest of your email setup and alerts you if anything changes.
Monitor it

What this tool checks

SPF (Sender Policy Framework) lists which mail servers are allowed to send email for your domain. This checker reads your SPF record, flags common problems (a missing or permissive all mechanism, too many DNS lookups, multiple SPF records), and shows it alongside your DKIM, DMARC, and MX so you see the whole email picture. It also surfaces the exact record so you can copy and fix it.

Frequently asked questions

What does the SPF all mechanism do?

The all mechanism at the end of an SPF record decides what happens to senders not listed: -all rejects them (recommended), ~all soft-fails (often quarantines), ?all is neutral, and +all allows anyone (never use this).

How many DNS lookups can SPF have?

SPF allows at most 10 DNS lookups (from include, a, mx, ptr, exists, redirect). Exceeding that causes a permerror and SPF fails, so this checker flags records that get close.

Can I have more than one SPF record?

No. RFC 7208 allows only a single SPF record per domain. Multiple SPF records are an error, so merge them into one.

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