What the email diagnostics tool checks

Our free email diagnostic gives you a one-off address, then grades the message you send it against every check below. Each result is ranked Pass, Info, Warning, or Critical, and the report's overall status is the worst finding. Here's what each check tests and why it matters.

Run a free diagnostic Deliverability vs placement
You get a one-off capture address — send any message to it from the system you want to test
Each message gets its own graded report across authentication, DNS, transport and reputation

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Message type & delivery path

Whether the mail arrived direct, forwarded, via a list or as a bounce - and why that changes how every other result should be read.

Deliverability vs placement

Getting accepted is not the same as landing in the inbox. What the diagnostic can prove, and what it can't.

Authentication

Who is allowed to send as your domain, and whether this message proved it. The single biggest lever on whether mail is accepted at all.

SPF

Is the sending IP authorised by the domain's SPF record - and is the record itself valid and within the lookup limit?

DKIM

Did the cryptographic signature verify, and is the published key strong enough to be trusted?

DMARC

Does the domain publish a policy, is it enforcing, and did this message pass alignment?

From alignment

Do the envelope sender and the visible From address line up the way DMARC needs them to?

ARC

For forwarded mail: is there an intact chain that lets the receiver recover the original authentication?

DNS & infrastructure

The DNS plumbing receivers cross-check before they trust a sending server at all.

MX records

Can the sending domain receive bounces and replies? A domain that can't is a strong spam signal.

Reverse DNS

Does the sending IP have a PTR record that forward-confirms? Most large providers require it.

EHLO hostname

Did the server greet with a real, fully-qualified hostname that resolves - or with junk?

Transport security

Whether mail to and from the domain travels encrypted, and resists downgrade attacks.

TLS in transit

Did this message arrive over an encrypted connection, and on a modern TLS version?

Inbound MX STARTTLS

An active probe of your own MX: does it offer STARTTLS with a valid certificate?

MTA-STS

Does the domain publish a policy that stops attackers stripping TLS from inbound mail?

TLS-RPT

Will the domain owner be told when TLS delivery to them fails?

Reputation & content

Signals about the sender's standing and the message itself that filters weigh heavily.

DNS blocklists

Is the sending IP listed on a major blocklist like Spamhaus? Listed IPs are rejected almost everywhere.

Policy disposition

A live preview: what a strict receiver applying these same results would do with the message.

Header hygiene

Are From, Date, Message-ID and other headers present, well-formed and plausible?

BIMI

Does the domain publish a record that lets supporting inboxes show your brand logo?
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