SPF Too Many DNS Lookups? Here’s How to Fix It

One of the most common SPF errors businesses encounter is the “Too Many DNS Lookups” issue. This problem often causes SPF validation failures, which can lead to:

• Emails landing in spam
• DMARC failures
• Authentication errors
• Reduced email deliverability

The issue usually appears as:

• SPF PermError
• SPF lookup limit exceeded
• Too many DNS lookups

This problem is especially common for businesses using multiple email services such as:

• Google Workspace
• Microsoft 365
• Mailchimp
• SendGrid
• CRM systems
• Cold email tools

In this guide, you’ll learn:

• What SPF lookup limits are
• Why SPF PermError happens
• How to reduce DNS lookups
• SPF flattening explained
• Best practices for SPF optimization

You can quickly test your SPF configuration using the LeadCanal Domain Scanner, which checks:

• SPF
• DKIM
• DMARC
• Authentication issues

You can also use:

• SPF Checker
• SPF Generator

for deeper SPF troubleshooting.

What is SPF PermError?

SPF PermError stands for Permanent Error. It occurs when a receiving mail server cannot properly process your SPF record.

One of the most common reasons is exceeding the SPF DNS lookup limit.

When this happens:

• SPF validation fails
• DMARC may fail
• Emails may go to spam
• Messages may be rejected

Mailbox providers treat SPF failures seriously because they affect sender trust and authentication.

Why SPF Has a 10 Lookup Limit

SPF records rely on DNS lookups to verify authorized mail servers.

However, to prevent excessive DNS queries and abuse, SPF standards limit domains to a maximum of 10 DNS lookups.

This rule is defined in SPF specifications and enforced by most major mailbox providers.

What Counts as a DNS Lookup?

Several SPF mechanisms generate lookups, including:

• include:
• a
• mx
• exists
• redirect

Each lookup consumes part of the 10-lookup limit.

Example:

v=spf1 include:_spf.google.com include:sendgrid.net ~all

Each include statement may generate multiple additional lookups internally.

What Causes Too Many Lookups?

Most SPF lookup problems happen because businesses continue adding email providers over time without optimizing their SPF records.

Multiple Third-Party Providers

Modern businesses often use many email services simultaneously.

Examples include:

• Marketing platforms
• CRM systems
• Support tools
• Transactional email providers
• Cold email software

Every additional provider may increase lookup usage.

Nested Include Statements

Some SPF records contain nested includes.

For example:

include:service1.com

may itself contain:

• multiple include statements
• redirects
• additional DNS queries

This quickly increases total lookups.

Old or Unused Services

Businesses often leave unused providers inside SPF records.

Over time, SPF records become bloated with:

• outdated platforms
• inactive marketing tools
• old mail systems

This unnecessarily consumes lookup limits.

How to Check SPF Lookups

Before fixing SPF issues, you should analyze your current SPF record.

A proper SPF analyzer helps identify:

• Lookup count
• Nested includes
• Invalid syntax
• Redundant entries

You can analyze your domain using:

• LeadCanal SPF Checker
• LeadCanal Domain Scanner

These tools help identify whether your SPF record exceeds safe limits.

How to Reduce SPF Lookups

Reducing SPF lookups usually involves simplifying and optimizing your SPF record.

Remove Unused Services

The easiest fix is removing providers you no longer use.

Review:

• CRM systems
• Marketing tools
• Transactional email services
• Outreach platforms

If a platform no longer sends emails for your domain:

• Remove its include statement

This immediately reduces lookup usage.

Consolidate Email Providers

Many businesses use overlapping services unnecessarily.

Instead of using:

• Multiple SMTP providers
• Several outreach platforms
• Duplicate marketing tools

consider consolidating systems where possible.

Fewer providers usually mean:

• Simpler SPF records
• Better deliverability management
• Easier troubleshooting

Use Subdomains for Different Services

Large organizations often separate sending systems using subdomains.

Examples:

• marketing.example.com
• support.example.com
• outreach.example.com

Each subdomain can have its own SPF record.

This reduces pressure on the primary domain’s SPF lookup count.

SPF Flattening Explained

SPF flattening is one of the most common solutions for excessive lookups.

What is SPF Flattening?

SPF flattening replaces include statements with direct IP addresses.

Instead of:

include:_spf.google.com

the SPF record contains:

• Actual sending IP ranges

This reduces live DNS lookups.

Benefits of SPF Flattening

Flattening helps:

• Reduce lookup counts
• Prevent SPF PermError
• Improve DNS efficiency

This is especially useful for:

• Large organizations
• Complex email infrastructures
• High-volume senders

Risks of SPF Flattening

Flattening also has drawbacks.

Some providers change IP ranges regularly.

If your flattened SPF record becomes outdated:

• Legitimate emails may fail SPF

This means flattened records require ongoing maintenance.

Example SPF Optimization

Many SPF records become unnecessarily large over time.

Poor SPF Example

v=spf1 include:a.com include:b.com include:c.com include:d.com include:e.com ~all

This setup may exceed lookup limits depending on nested records.

Optimized SPF Example

v=spf1 include:_spf.google.com include:sendgrid.net ~all

Simplifying providers reduces lookup risks significantly.

Common SPF Lookup Mistakes

Many SPF errors happen because of incorrect configuration practices.

Multiple SPF Records

A domain should only have one SPF record.

Incorrect setup:

v=spf1 include:_spf.google.com ~all

and

v=spf1 include:sendgrid.net ~all

This cuses SPF failure.

Instead, combine everything into one SPF record.

Excessive Includes

Adding too many providers without monitoring lookup counts eventually causes problems.

Always review:

• Total lookups
• Nested includes
• Third-party dependencies

Best Practices for SPF Management

Proper SPF maintenance helps avoid long-term deliverability issues.

Keep SPF Records Simple

Avoid overly complex SPF structures.

Simpler records are:

• Easier to maintain
• Easier to troubleshoot
• Less likely to exceed limits

Audit Providers Regularly

Review sending services regularly and remove unused platforms.

This helps:

• Reduce complexity
• Improve security
• Maintain deliverability

Combine SPF with DKIM and DMARC

SPF alone is not enough for modern email authentication.

For stronger protection, combine SPF with:

• DKIM
• DMARC

You can verify all records using:

• LeadCanal Domain Scanner
• SPF Checker
• DKIM Checker
• DMARC Checker

FAQs

What Happens After 10 SPF Lookups?

Once the SPF lookup limit is exceeded:

• SPF fails with PermError
• DMARC may fail
• Emails may go to spam or get rejected

Does Google Enforce SPF Lookup Limits?

Yes.

Major providers like:

• Google Workspace
• Microsoft 365

enforce SPF lookup limits.

Is SPF Flattening Required?

Not always.

Smaller SPF records usually do not require flattening.

However, businesses with:

• Multiple providers
• Large infrastructures
• Complex authentication setups

may benefit from flattening.

What is Email Spoofing?

Email spoofing happens when attackers forge email headers to make messages appear as though they came from a trusted sender.

The attacker may impersonate:

• Your business domain
• Your CEO
• Your support department
• Vendors or suppliers
• Financial institutions

Spoofed emails are commonly used in:

• Phishing attacks
• Business Email Compromise (BEC)
• Invoice fraud
• Credential theft

Without proper email authentication, mailbox providers may struggle to verify whether emails are legitimate.

How Spoofing Works

Email was originally designed without strong authentication controls. Because of this, attackers can manipulate sender information relatively easily if protections are not in place.

From Address Manipulation

Attackers commonly spoof the visible “From” address.

For example:

billing@example.com

Even if the attacker does not own the domain, they may still attempt to make the email appear legitimate.

To the recipient:

• The message may look authentic
• The sender appears trusted
• The email may create urgency or fear

This is why authentication protocols are so important.

Fake Domains and Lookalike Domains

Some attackers also register lookalike domains.

Examples:

• examp1e.com
• exarnple.com
• example-support.com

These domains are designed to confuse users visually.

Even with DMARC protection, businesses should monitor for lookalike domain abuse.

Financial Fraud

Business Email Compromise attacks often target:

• Finance teams
• Executives
• Vendors

Attackers may request:

• Wire transfers
• Invoice payments
• Gift card purchases

These scams cause billions of dollars in losses globally every year.

Brand Reputation Damage

If attackers spoof your domain:

• Customers may lose trust
• Your brand reputation may suffer
• Email providers may distrust your domain

This can also reduce email deliverability for legitimate messages.

How SPF Helps Prevent Spoofing

SPF (Sender Policy Framework) helps specify which servers are allowed to send emails on behalf of your domain.

When mailbox providers receive an email, they:

1. Check the sending server
2. Verify the SPF record
3. Determine whether the sender is authorized

Example SPF Record

v=spf1 include:_spf.google.com ~all

This record authorizes:

• Google Workspace mail servers

to send emails for the domain.

SPF Limitations

SPF improves security, but it has limitations.

For example:

• SPF can break during forwarding
• Attackers may still spoof visible sender addresses
• SPF alone does not fully stop spoofing

This is why SPF should always be combined with DKIM and DMARC.

You can verify SPF records using the LeadCanal SPF Checker.

How DKIM Works

When an email is sent:

• The server signs the message using a private key
• A public key is published in DNS
• Receiving servers validate the signature

If the signature fails:

• The email may be treated as suspicious

Why DKIM is Important

DKIM helps:

• Protect message integrity
• Prevent tampering
• Improve email trust

Unlike SPF, DKIM signatures often survive forwarding, making DKIM especially valuable for reliable authentication.

You can test DKIM using the LeadCanal DKIM Checker.

How DMARC Stops Spoofing

 is the strongest layer of email authentication because it combines SPF and DKIM with policy enforcement.

DMARC tells mailbox providers:

• How to verify emails
• How to handle failures
• How to report suspicious activity

DMARC Policies

DMARC supports three policy levels.

p=none

p=none

Used for monitoring only.

p=quarantine

p=quarantine

Suspicious emails may be sent to spam folders.

p=reject

p=reject

Failed emails are rejected completely.

This provides the strongest protection against spoofing.

Why DMARC is Effective

DMARC helps:

• Block spoofed emails
• Protect brand identity
• Improve deliverability
• Monitor unauthorized senders

It also introduces alignment checks, which help prevent attackers from spoofing visible sender domains.

You can validate DMARC records using the LeadCanal DMARC Checker

Enable Multi-Factor Authentication (MFA)

MFA helps protect accounts even if passwords are stolen.

Common MFA methods include:

• Authenticator apps
• Security keys
• Biometrics
• SMS verification

Providers like:

• Microsoft 365
• Google Workspace

strongly recommend MFA for business accounts

Monitor Domain Activity

Businesses should regularly monitor:

• DMARC reports
• Failed authentication attempts
• Suspicious sending activity

This helps detect spoofing attempts early.

How to Monitor Spoofing Attempts

DMARC reports provide visibility into who is sending emails using your domain.

These reports help identify:

• Unauthorized senders
• Failed authentication
• Spoofing attempts

Aggregate Reports

Aggregate reports summarize:

• SPF results
• DKIM results
• Sending IP addresses
• Authentication statistics

Example DMARC tag:

rua=mailto:dmarc@example.com

Protect Non-Sending Domains

Defensive domains and parked domains should also have:

• SPF records
• DMARC reject policies

This prevents attackers from abusing unused domains.

Move Gradually to p=reject

The safest DMARC deployment path is:

1. p=none
2. p=quarantine
3. p=reject

This minimizes the risk of accidentally blocking legitimate emails.

FAQs

Can Email Spoofing Be Completely Stopped?

No security solution is perfect, but proper SPF, DKIM, and DMARC configuration significantly reduces spoofing risks.

Combined with MFA and user training, businesses can greatly improve protection.

Does DMARC Protect Subdomains?

Yes.

DMARC supports subdomain policies using the:

sp=

tag.

This allows businesses to define rules for subdomains separately.

Is SPF Alone Enough?

No.

SPF should always be combined with:

• DKIM
• DMARC

for stronger protection and better deliverability.

Final Thoughts

Email spoofing remains one of the biggest cybersecurity threats facing businesses today. Attackers constantly target trusted brands to steal information, commit fraud, and spread phishing attacks.

Proper email authentication is one of the best ways to protect your domain, your customers, and your reputation.

You can analyze your full authentication setup using the LeadCanal Domain Scanner.

For individual testing and troubleshooting, use:

• SPF Checker
• DKIM Checker
• DMARC Checker

If your organization needs help with:

• Email authentication
• DMARC implementation
• Domain protection
• Cold email infrastructure
• Deliverability optimization

you can contact LeadCanal for professional support.