MX
MX records tell other mail servers where to deliver messages for your domain. They are the first sign that a domain can receive business email.
Email DNS Tool
Email Deliverability Checker
Inspect the public DNS configuration used for business email. Check MX, SPF, DKIM, DMARC and other email security records in one report. This does not send a message or test whether it reaches an inbox.
Email Readiness Summary
Email health report
Enter a public domain to check MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, BIMI, and basic website context.
A DNS score is a starting point
A domain can publish SPF, DKIM, and DMARC and still have mail rejected because the actual sender is misconfigured or has a poor reputation. This checker cannot measure inbox placement, inspect a sent message, or confirm that a provider is signing it. Its SPF lookup count covers visible mechanisms, not every nested include.
Example: DKIM is not detected
A provider might sign with a selector outside the common names tested here. Find the selector in the provider’s admin settings or the s= field of a sent message’s DKIM-Signature header, enter it in the checker, and repeat. Finding the public key confirms publication; use the receiving service’s authentication results to check whether that message’s signature passed. You do not need to upload a message here.
Before tightening DMARC enforcement, inventory legitimate sending services and check that their messages pass DMARC alignment. Use your provider’s guidance and aggregate reports; a high score on this page does not establish that every sender is ready. See how the checks work.
Email deliverability records explained
SPF
SPF lists the services allowed to send mail for your domain. A single, well-scoped SPF record helps reduce spoofing and delivery failures.
DKIM
DKIM signs outgoing mail with a domain key. The checker tests common selectors and any selectors you enter for the domain.
DMARC
DMARC connects SPF and DKIM results to a policy. Monitoring can start with p=none, then move to quarantine or reject after legitimate senders pass.
MTA-STS and TLS-RPT
These records strengthen encrypted mail transport and reporting. They are useful security upgrades after the core mail records are healthy.
BIMI
BIMI can publish a brand logo for supported inboxes. It normally depends on strong DMARC enforcement and brand validation.
Email deliverability FAQ
What does an email deliverability checker test?
It checks the DNS records that affect business email delivery and authentication, including MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, and BIMI.
Why do MX records matter?
MX records tell other mail servers where to deliver email for your domain. Without MX records, a domain may not be able to receive email.
What are SPF, DKIM, and DMARC?
SPF lists approved senders, DKIM signs outgoing messages, and DMARC tells receivers what to do when authentication fails.
Why might DKIM not be detected?
DKIM is selector-based. Port233 tests common selectors, but your provider may use a different selector that needs to be entered manually.
Does BIMI improve deliverability?
BIMI is an advanced brand indicator. It can help eligible brands show a logo in supported inboxes, but SPF, DKIM, and enforced DMARC should come first.
Can Port233 help fix email DNS records?
Yes. Port233 and Securewire can help configure DNS, Microsoft 365, Google Workspace, SPF, DKIM, DMARC, and related mail security records.
Need help fixing DNS or business email?
Port233 and Securewire help small businesses configure Microsoft 365, Google Workspace, DNS, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, and practical email security controls.
Port233 Toolkit
Documenting email security work?
Use Cyber Essentials and the IT Consultant Bundle Pack to record MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, provider details, and client handover notes.
Some resources link to Port233 products hosted on Gumroad. Purchases are completed securely through Gumroad.
Useful external services
Recommended external tools
If your email DNS needs changes, you may need a reliable email host, DNS provider, or privacy-focused business suite to manage the wider setup.
Proton Mail
Useful for encrypted email, custom-domain mail, email aliases, and privacy-focused business communication.
Explore Proton MailSome external links may be affiliate links. Port233 may earn a commission if you purchase through them, at no extra cost to you. Read the affiliate disclosure.