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Know why your email lands — or doesn't.

SenderProbe reads your domain the way a receiving mail server does, and tells you which part is the problem.

Check my domain

The checks

What it checks

SenderProbe reads the same signals a receiving mail server does — the records you publish, the reputation of the address you send from, and the message itself — and tells you which one is the problem.

blacklist zones queried on every reputation check
38
domain that deliverability test addresses are issued on
test.senderprobe.com
API version answering this page right now
dev

The four gates a receiver walks

Each lookup returns the records it found plus findings graded PASS, WARN or FAIL — the sentence that says what to change. Long probes stream their progress, a bulk job covers up to 100 domains in one pass, and every name below links to the page describing what that check reads.

  1. Routing Which hosts are told to accept mail for the domain, and whether they answer.
  2. Authentication Whether the receiver can prove the message came from you, and what your policy asks it to do when it cannot.
  3. Reputation What the sending address looks like to a filter before it reads a single word.
  4. Transport and ownership The live SMTP conversation, the certificate it offers, and the records and registration behind the domain.

Beyond the lookups

The checks are the floor. What the workspace adds is everything that keeps them running and turns an answer into something you can act on.

  • Inbound deliverability test SenderProbe hands you an address; you send it a message. The report scores it out of 10, prints the spam-filter total against the threshold that would have blocked it, and breaks the result into filter, authentication, blacklist and content sections.
  • Header analysis Paste the raw headers of a message that went wrong. You get the delivery path hop by hop with the delay introduced at each one, the protocol, TLS and IP it used, and the SPF, DKIM, DMARC and ARC results as the receiver saw them.
  • Monitoring that deduplicates Blacklist, DNS, SMTP, TLS, WHOIS and DMARC monitors re-run on an interval you set. A failure that persists folds into one incident with a timeline of events instead of a fresh alert every cycle, and you acknowledge, mute or resolve it in place.
  • DMARC aggregate ingestion Point your rua= tag at the address your workspace is given, or upload reports you already have. Every sending source is listed with its volume and SPF, DKIM and DMARC pass rates, so you can see what aligns before you tighten the policy.
  • Share links and a documented API Publish a status page, a deliverability report or a single lookup as a link anyone can open and you can switch off. Every check in the product is also an endpoint, with scoped keys and an OpenAPI document generated by the server itself.

Read the reference before you change a record

A check tells you what is wrong; the reference tells you why it is wrong and what a correct record looks like. Every mechanism SenderProbe inspects has a guide, every lookup has a page describing what it reads, and every term either one uses has a definition. None of it needs an account.

How it works

Four steps, in the order you will actually take them.

  1. Add the domain you send from

    SenderProbe normalises what you paste, then sweeps it immediately: MX and the hosts behind it, SPF, DKIM, DMARC, every blacklist zone it watches, and a live SMTP connection to the mail exchanger.

  2. Read findings, not raw records

    Each check comes back graded PASS, WARN or FAIL with a description of what it means. An SPF record close to the ten-lookup limit, a DKIM selector with a short key, a certificate about to expire — all of it says what to change.

  3. Turn the checks into monitors

    Any check can run on a schedule. When a result turns, SenderProbe opens one incident and appends to its timeline rather than alerting again on every cycle, and notifies the email, Slack or webhook channels you have verified.

  4. Publish what you want others to see

    A status page, a deliverability report or a single lookup can each be shared as a public link, with view counts and an off switch. Everything else stays inside the workspace.

Common questions

The lookups above run for free, with no account. These are the questions that come up first.

Can I check MX, SPF, DKIM and DMARC records without an account?
Yes. Each tool has its own free page — MX, A, NS, TXT and PTR records, SPF, DKIM and DMARC, blacklists, SMTP and WHOIS — and runs immediately. Enter a domain and the result renders on the page. No sign-up is needed to run a check.
Does SenderProbe send mail to the domain I check?
No. A lookup only reads public DNS records, blacklist zones and the SMTP banner a mail server publishes. It never sends mail to the domain you check; the only place SenderProbe accepts mail is a deliverability test you deliberately send to it.
What does a workspace add over the free checks?
The free check is the same diagnostic, run once and unrecorded. A workspace monitors the domain on a schedule, keeps a history of every check, runs bulk checks across many domains, ingests DMARC aggregate reports, and offers share links and a documented API.

Free during beta

SenderProbe is in beta, and everything in it is free while it is — the lookups, the monitors, the alerts, the reports and the API. There are no paid plans to choose between yet; when there are, this page will say so.

  • Every lookup tool, on demand
  • Scheduled monitors, incidents and alerting
  • DMARC aggregate reports
  • Header analysis and deliverability tests
  • Team seats and API keys

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