How Businesses Can Verify Their Email Infrastructure

Email is one of the few business systems whose configuration is partly public. The DNS records that control where your mail goes, who can send on your behalf, and how spoofing is handled are visible to anyone — including attackers. That makes periodic verification less of a nicety and more of a hygiene practice. This article is a practical checklist an IT team can work through in an afternoon to confirm that a domain's email infrastructure is correctly configured and properly defended.

Why Verification Is Worth the Time

Most email problems are silent until they are not. A misconfigured SPF record might not block mail today, but it can quietly hurt deliverability over time. A missing or permissive DMARC policy can let spoofers impersonate your domain until a phishing report lands in your inbox. Verifying your records on a regular schedule — and after any migration, acquisition, or provider change — catches these issues while they are still cheap to fix. The four records below are the full scope of the audit. For a conceptual overview of what each one does, start with what DNS records tell you about an email domain.

The Verification Checklist

1. Audit your MX records

Your MX records tell the world where to deliver mail for your domain, so they are the first thing to confirm. Check that the hostnames match your intended provider and that no stale or unauthorised records remain from a previous setup.

• Query your MX records with dig MX yourdomain.com or the MX Record Checker.
• Confirm every hostname belongs to your current provider (for example, aspmx.l.google.com for Google Workspace or mail.protection.outlook.com for Microsoft 365).
• Remove any records pointing at decommissioned or legacy servers.
• Verify that priority values match your provider's recommended configuration and that redundancy is in place if the provider supports it.

For the priority and redundancy mechanics, see understanding MX records for business email, and for the record format itself, our MX record primer.

2. Verify your SPF record

SPF lists the servers authorised to send mail on your domain's behalf. An outdated or overly permissive SPF record can hurt deliverability or, worse, authorise senders you did not intend to allow.

• Query the TXT record set with dig TXT yourdomain.com and find the entry starting with v=spf1.
• Confirm the include: mechanisms match your current provider and any approved third-party senders (marketing, transactional, support tools).
• Remove include: references to services you no longer use.
• Check the all qualifier. ~all (soft fail) is a safe starting point; -all (hard fail) is stricter and recommended once you are confident no legitimate senders are missing.
• Watch the lookup limit. SPF allows at most 10 DNS lookups via include and redirect. Too many nested includes can cause the record to fail silently.

3. Check your DKIM configuration

DKIM signs outgoing messages so receivers can verify they were sent by your domain's key and unchanged in transit. A missing or broken DKIM setup weakens both deliverability and DMARC alignment.

• Identify your DKIM selectors. Check your provider's admin console for the selector names in use, or inspect a sent message's DKIM-Signature header for the s= value.
• Query each selector's public key with dig TXT selector._domainkey.yourdomain.com and confirm the key is present and valid.
• If your provider uses CNAME-based DKIM, confirm the CNAME resolves to the provider-managed key hostname.
• Send a test message to a service that reports authentication results and confirm DKIM passes (the pass result should appear alongside SPF).

4. Review your DMARC policy

DMARC tells receiving servers what to do when SPF or DKIM alignment fails. It is the policy layer that turns your other records into enforcement, and it is the one most often left in a permissive state.

• Query the record with dig TXT _dmarc.yourdomain.com.
• Check the policy: p=none monitors only, p=quarantine moves failures to spam, p=reject drops them outright.
• Confirm the RUA (rua=) reporting address is set so you receive aggregate feedback on authentication failures.
• Plan a path from p=none to p=reject. Start in monitor mode, review the reports for any legitimate senders that fail alignment, fix the gaps, then step up to quarantine and finally reject.

For how these records combine into a complete picture, revisit what DNS records tell you about an email domain.

5. Test with the Email Provider Filter

Once the records are corrected, confirm the outside world sees the result you expect. The Email Provider Filter performs the same MX and SPF lookups any sender would, so it is a quick external validation that your domain resolves to the right provider. Run your own domain through it and confirm the reported provider matches your actual setup. If it does not, something in your MX or SPF records is still off — and the tool's underlying records will show you which one.

For a single-domain, full-detail view, the Email Domain Checker surfaces all four record types at once, and the Provider Lookup page confirms the provider identification specifically.

Build It Into Your Routine

A one-time audit is a good start, but email infrastructure drifts. New third-party senders get added, old ones get forgotten, and migrations leave stray records behind. A few habits keep verification ongoing:

• Schedule a quarterly review. Re-run the five-step checklist every few months, or more often if your organisation changes providers or adds marketing/transactional senders frequently.
• Audit after every change. Any migration, acquisition, or onboarding of a new sender should trigger a fresh verification pass.
• Monitor DMARC reports. The aggregate reports you configured in step four are a continuous feedback loop — review them for unexpected failures rather than only when a problem is reported.
• Document the intended state. Keep a record of what your MX, SPF, DKIM, and DMARC entries should look like, so drift is obvious on the next check.

The Checklist in Short

1. Audit MX records — right provider, no stale hosts, correct priorities.
2. Verify SPF — current include list, sensible all qualifier, under the 10-lookup limit.
3. Check DKIM — selectors present, keys valid, test message passes.
4. Review DMARC — policy staged toward reject, reporting configured.
5. Test with the Email Provider Filter — external validation that the world sees what you intend.

Work through these five steps and you will have confirmed the four records that matter, caught the drift that builds up over time, and validated the result from the outside. That is what it takes to verify your email infrastructure — and with the tools linked above, it is a manageable afternoon's work. For the broader context behind each step, how to find the email provider behind a domain and how to check the email provider of a business domain are useful companions.