Email Deliverability Check

Analyse your domain’s email authentication, routing, and reputation in one scan.

Press Enter or , to add each selector. Scanned alongside our 130+ built-in list.

signal.org
Email Deliverability
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D 66
signal.org
Acceptable setup — a few gaps to address.
7 passed 2 warnings 1 failed Export PDF
Mail Routing
Verifies that your domain has valid mail server records and that they resolve correctly.
PASS
MX Records Mail server routing

5 MX record(s) found.

MX records define where email for your domain is delivered. Without them, no mail can be received. Multiple MX records with different priorities provide automatic failover. An RFC 7505 Null MX (priority 0, host “.”) is detected and shown here — it explicitly declares the domain does not accept email.

PriorityHostnameType
1 aspmx.l.google.com Mail server
5 alt1.aspmx.l.google.com Mail server
5 alt2.aspmx.l.google.com Mail server
10 aspmx3.googlemail.com Mail server
10 aspmx2.googlemail.com Mail server
Authentication
The three-pillar framework that proves your emails are legitimate and prevents spoofing.
WARN
!
SPF Sender Policy Framework Soft Fail (~all)

SPF uses ~all (soft fail). Consider upgrading to -all.

SPF lists which IP addresses are authorised to send email as your domain. A hard fail (-all) is strongest — receivers reject anything not on the list outright.

v=spf1 include:_spf.google.com ~all
Mechanism Breakdown 1/10 DNS lookups
Q Type Value Status Notes & Guidance
+ include _spf.google.com DNS
~ all
DKIM DomainKeys Identified Mail

DKIM records found for selector(s): google. Provider: Google Workspace.

DKIM adds a cryptographic signature to every outgoing message. Receiving servers use your public key (published in DNS) to verify the message hasn't been altered in transit.

199 selectors scanned 1 found Google Workspace
google._domainkey Google Workspace RSA  1024-bit collapse
Tag Value Status Notes & Guidance
v= DKIM1
k= rsa
p= MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCSYE2OjxFNy7pT…
!
DMARC Domain-based Message Authentication p=quarantine

DMARC policy is quarantine. Consider upgrading to reject.

DMARC ties SPF and DKIM together with an enforcement policy. p=reject is the gold standard — it instructs receivers to block unauthenticated mail entirely and protects your domain from spoofing.

v=DMARC1; p=quarantine; pct=100; rua=mailto:dmarc@signal.org
Tag Breakdown
Tag Value Status Notes & Guidance
v= DMARC1
p= quarantine ! Policy 'quarantine' sends suspicious mail to spam — consider upgrading to reject
→ Fix: Change to p=reject for maximum protection once you are confident your SPF and DKIM are correct
pct= 100
rua= mailto:dmarc@signal.org
Reports to: mailto:dmarc@signal.org
DMARC Reports Aggregate & forensic reporting

DMARC reporting configured. Aggregate (rua): mailto:dmarc@signal.org.

DMARC can send you daily XML reports (rua=) about which servers are sending mail as your domain and whether they pass authentication. Forensic reports (ruf=) include individual failure samples. Without these you are flying blind.

Aggregate (rua) mailto:dmarc@signal.org

Tip: Add ruf=mailto:forensic@yourdomain.com to receive individual failure samples for investigation.

Transport Security
Ensures email is delivered over encrypted connections and that TLS failures are reported.
PASS
MTA-STS Enforce inbound TLS

MTA-STS is configured.

MTA-STS forces other mail servers to use TLS encryption when delivering to you, blocking downgrade attacks that would expose messages in transit. It works together with TLSRPT for visibility.

v=STSv1;id=20260327162351;
TLSRPT TLS failure reporting

TLSRPT is configured.

When TLS negotiation fails during inbound delivery, TLSRPT sends you a structured JSON report. This lets you detect misconfigured sending servers or active downgrade attacks targeting your MTA-STS policy.

v=TLSRPTv1;rua=mailto:smtp-tls-reports@signal.org;
Brand & Reputation
Brand logo visibility, reverse DNS matching, and blacklist status of your mail servers.
FAIL
i
BIMI Brand logo in email clients

No BIMI record. BIMI enables brand logo display in supporting email clients.

BIMI lets you display your verified brand logo in supporting inboxes (Gmail, Apple Mail, Yahoo). It requires DMARC with quarantine or reject, and an SVG logo hosted at a published URL.

PTR Records Reverse DNS for MX hosts

All MX server IPs have valid PTR records with forward-confirmed reverse DNS (FCrDNS).

Checks that each MX server IP has a PTR record and that the PTR hostname forward-resolves back to the same IP (FCrDNS). Most spam filters require FCrDNS to pass — a missing or non-confirming PTR raises the spam score of your outbound mail.

MX HostIPVerPTRMatch
aspmx.l.google.com 142.251.127.27 IPv4 lcfrai-in-f27.1e100.net
aspmx.l.google.com 2a00:1450:4001:c21::1b IPv6 lcfrai-in-f27.1e100.net
alt1.aspmx.l.google.com 192.178.213.26 IPv4 yugrqzs-in-f26.1e100.net
alt1.aspmx.l.google.com 2a00:1450:4010:c22::1b IPv6 yulpptr-in-f27.1e100.net
alt2.aspmx.l.google.com 142.251.127.26 IPv4 lcfrai-in-f26.1e100.net
alt2.aspmx.l.google.com 2404:6800:4000:1025::1b IPv6 lcbomp-in-f27.1e100.net
Blacklist Check 8 DNSBL zone spot-check

Listed on: 2a00:1450:4001:c21::1b on dnsbl.spfbl.net.

Checks whether your MX server IPs (IPv4 and IPv6) appear on major spam blocklists (Spamhaus, SpamCop, Barracuda, SORBS, and others). A single listing can cause severe delivery failures at major providers.

142.251.127.27 2a00:1450:4001:c21::1b 192.178.213.26 2a00:1450:4010:c22::1b 142.251.127.26 2404:6800:4000:1025::1b 60 zone checks
LISTED 2a00:1450:4001:c21::1b on dnsbl.spfbl.net
Action required: Visit each blocklist above to request delisting. A listing on Spamhaus or Barracuda can cause rejection at major email providers.
Score Breakdown
Reference Guide