Email deliverability is often treated as a marketing problem, but a large part of it starts much deeper: DNS configuration.
Before an email provider can trust a message, it may need to verify information published in the sender domain's DNS records.
For developers, sysadmins, and anyone managing business email infrastructure, understanding these records can save hours of troubleshooting.
What Does DNS Have to Do With Email?
DNS doesn't just connect domain names to IP addresses.
It can also store information used by email systems, including:
MX records
TXT records
SPF policies
DKIM public keys
DMARC policies
CNAME records
A missing or incorrect DNS record can cause email authentication to fail even when the email platform itself appears to be configured correctly.
- MX Records
MX stands for Mail Exchange.
These records tell other mail servers where email for a domain should be delivered.
For example, if a business uses Google Workspace or Microsoft 365, its MX records normally point toward that provider's mail infrastructure.
Incorrect MX records can interfere with receiving email.
- SPF Records
SPF information is normally published through a TXT record.
SPF defines which servers or services are authorized to send email for a domain.
A typical configuration may need to account for:
Business email provider
CRM
Transactional email service
Newsletter platform
Outreach platform
One common mistake is keeping multiple separate SPF policies instead of maintaining a valid consolidated configuration.
- DKIM Records
DKIM uses public-key cryptography to help verify outgoing messages.
The sending provider signs the email using a private key.
A corresponding public key is published in DNS under a selector.
The receiving server retrieves this public key and uses it to verify the signature.
If the selector or DNS record is incorrect, DKIM verification can fail.
- DMARC Records
DMARC builds on SPF and DKIM.
It allows domain owners to specify how receiving mail servers should handle messages that fail authentication and alignment checks.
Common policies include:
p=none
p=quarantine
p=reject
DMARC can also provide reporting that helps administrators identify unauthorized senders or configuration problems.
Why DNS Problems Are Easy to Miss
DNS configuration becomes complicated when several services send email for the same domain.
For example, a company may simultaneously use:
Google Workspace
HubSpot
Mailchimp
A support platform
Transactional email infrastructure
A sales outreach platform
Over time, services get added or removed while old DNS records remain.
That's why periodic DNS audits are useful.
How to Check a Domain's DNS Records
You can query DNS records using command-line tools such as:
nslookup example.com
or:
dig example.com
For TXT records:
dig TXT example.com
For MX records:
dig MX example.com
If you prefer a browser-based option, you can also use the LeadCanal DNS Lookup Tool to inspect a domain's DNS records without running commands locally.
A Simple Email DNS Checklist
Before troubleshooting an email-deliverability problem, check:
MX records point to the correct provider
SPF exists and includes legitimate senders
DKIM keys are published correctly
DKIM selectors match the sending service
DMARC exists
Old email-service records have been removed
DNS changes have propagated
There are no obvious duplicate or conflicting records
DNS Is Only Part of Deliverability
Correct DNS configuration doesn't guarantee inbox placement.
Mailbox providers can consider other factors such as:
Sender reputation
Bounce rates
Spam complaints
Sending behavior
Recipient engagement
Email content
List quality
However, DNS and authentication provide the technical foundation that should be checked before investigating more complicated deliverability problems.
Final Thoughts
When email authentication fails, don't immediately assume the problem is your email platform.
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