SPF Record Too Many Lookups? How to Fix the 10-Lookup Limit

Zeeshan Waheed
8 min read
Cold Email Infrastructure

You set up SPF.

You added includes for SendGrid, HubSpot, Mailchimp, ActiveCampaign, your mail provider, and a few others.

Then you checked SPF at mxtoolbox.com.

Result: "Fail. Too many DNS lookups (12 found, limit is 10)."

Emails are bouncing. SPF is broken. This is a common problem when you use multiple email services.

This post shows you what the 10-lookup limit is, why it exists, and how to fix it using SPF flattening.

What Is the SPF 10-Lookup Limit?

SPF (Sender Policy Framework) works by doing DNS lookups.

ISPs query your SPF record: "Can this IP send for yourdomain.com?"

Your SPF record says: "Let me check... SendGrid can, HubSpot can, Mailchimp can..."

Each "check" = 1 DNS lookup.

The limit: ISPs will follow maximum 10 DNS lookups per SPF record. After 10, they stop and reject the SPF as "too complex."

Result: SPF fails. Email bounces.

Why This Happens (Multiple Email Services)

You probably use multiple email services:

  • HubSpot for CRM email
  • Mailchimp for newsletter
  • SendGrid for transactional emails
  • Instantly or SmartLead for cold email
  • Your mail server for regular email
  • Maybe Zapier or Make.com for automation (which also send email)

Each service needs an SPF include:

`

v=spf1

include:sendgrid.net

include:hubspot.com

include:mailchimp.com

include:instantly.ai

include:smartlead.ai

include:your-mail-server.com

include:zapier.com

include:make.com

~all

`

That's 8 includes. Plus any A, MX, or IP records in your SPF (each counts as 1 lookup).

Example: include:sendgrid.net = 1 lookup. But sendgrid.net itself might reference other includes internally. Each one counts. Total: might be 2-3 lookups for just SendGrid.

You can easily hit 10+ lookups with just 3-4 email services.

How to Diagnose: Check Your SPF Lookup Count

  1. Go to mxtoolbox.com
  2. Click "SPF Record"
  3. Enter your domain
  4. Check the result
  5. MXToolbox will tell you: "X DNS lookups found" (X should be 10 or below)

If X is 11 or more: You have too many lookups.

MXToolbox also shows you where each lookup is coming from:

Example result:

`

Lookup 1: yourdomain.com (A record)

Lookup 2: sendgrid.net

Lookup 3: sendgrid.net → sendgrid-net.spf.protection.outlook.com → lookup 4

Lookup 4: (from sendgrid chain)

Lookup 5: hubspot.com

...

Total: 12 lookups (FAIL - limit is 10)

`

This tells you which service is consuming the most lookups.

Fix 1: Remove Unnecessary Email Services from SPF

If you have 8 email services but only 2 are actively sending, remove the unused ones.

How to identify unused services:

  1. Check your SPF record
  2. Ask yourself: Which services actually send email from yourdomain.com?
  3. Remove any that don't (or shouldn't)

Example:

  • Using HubSpot CRM: Keep in SPF
  • Using Mailchimp newsletter but didn't send in 6 months: Remove
  • Using Zapier to send notifications: Keep
  • Using old email service that's deprecated: Remove

The fix:

  1. Log into your domain registrar
  2. Find DNS/DNS Records
  3. Edit your SPF record
  4. Remove "include:service-i-dont-use.com"
  5. Save
  6. Wait 24 hours
  7. Re-check at mxtoolbox.com

Example before/after:

Before (12 lookups):

`

v=spf1 include:sendgrid.net include:hubspot.com include:mailchimp.com

include:instantly.ai include:smartlead.ai include:old-service.com

include:zapier.com include:make.com ~all

`

After (8 lookups):

`

v=spf1 include:sendgrid.net include:hubspot.com include:instantly.ai

include:smartlead.ai include:zapier.com include:make.com ~all

`

Removed: mailchimp.com, old-service.com

Result: Dropped from 12 to 8 lookups. SPF passes.

This fixes 30-40% of SPF lookup problems.

Fix 2: SPF Flattening (Complex, Usually Requires Professional Help)

If you have many email services and can't remove any, you need SPF flattening.

Flattening replaces include:service.com with the actual IP addresses that service uses.

Why this matters:

  • include:sendgrid.net = 1-2 lookups (depends on sendgrid's SPF structure)
  • Flattened = list of IPs with no includes = 0 additional lookups

Example:

Before (flattening):

`

v=spf1 include:sendgrid.net include:hubspot.com ~all

`

After (flattening):

`

v=spf1 ip4:192.0.2.1 ip4:192.0.2.2 ip4:192.0.2.3 ~all

`

The IPs are SendGrid's and HubSpot's actual sending IPs.

Downside of flattening:

  • When SendGrid adds new IPs, you have to update your SPF manually
  • Your domain host needs to do this, it's not automatic
  • Requires quarterly or annual maintenance

Why not flatten everything:

  • Too many IPs to list
  • SPF record has size limits
  • Becomes hard to manage

When to flatten:

  • You have 1-2 high-volume email services
  • You have control over those IPs (they're stable)
  • You can maintain it quarterly

How to flatten (involves your domain host):

  1. Contact your domain registrar (GoDaddy, Namecheap, etc)
  2. Say: "I need SPF flattening for my domain. I have too many includes."
  3. Provide list of services: SendGrid, HubSpot, Instantly, etc
  4. They'll contact each service and get their IPs
  5. They'll replace includes with IP list
  6. They'll test and implement
  7. You'll get new SPF record to use

Cost: Usually free if you're a customer. Sometimes $25-50 if you're not.

Time: 1-2 weeks.

We handle SPF flattening for clients at enterprise scale. If you have 100+ inboxes and complex infrastructure, this becomes necessary.

Use fewer email services.

Instead of 8, use 3-4.

Example consolidation:

  • Use Instantly (cold email) + HubSpot (CRM) + SendGrid (transactional)
  • Remove: Mailchimp (use HubSpot newsletter), Zapier (use HubSpot automation)
  • Result: Lookups drop from 12 to 6

This is the easiest fix.

Many companies use redundant services without realizing it.

Audit your email services:

  1. List every service that sends email from your domain
  2. Ask: Is this necessary?
  3. Consolidate where possible
  4. Remove truly unused ones
  5. Result: Fewer lookups

SPF Best Practices (Prevent the Problem)

Once you fix SPF, keep it under 10 lookups:

Rules:

  1. Use 3-4 primary email services max
  2. If adding new service, remove old one first
  3. Use service consolidation (e.g., HubSpot does CRM + email + SMS)
  4. Monitor SPF monthly (use mxtoolbox.com)
  5. Document which services you have and why

Maintenance:

  • Monthly: Check SPF at mxtoolbox.com
  • Quarterly: Audit email services (still need them all?)
  • Annually: Review total lookups (should stay under 10)

Real Example: SPF Flattening at Scale

One enterprise client had 50+ inboxes across multiple domains.

Situation:

  • 8 different email services sending
  • 5 of them sending for each domain
  • SPF lookups: 15-18 per domain
  • Emails bouncing due to SPF fail

What we did:

  1. Identified which services were redundant (could consolidate)
  2. Consolidated from 8 services to 4
  3. Reduced lookups from 15+ to 8

For 2 core services (SendGrid and Instantly), did SPF flattening to get down to 6 lookups total.

Results:

  • SPF: Now passes on all domains
  • Bounce rate: Dropped from 8% to 2%
  • Deliverability: Improved 60% → 82%

Total time: 20 hours of work (mostly consolidation planning, flattening, and testing).

Troubleshooting: SPF Still Failing After Fixes

If SPF still shows fail after removing services or flattening:

Check 1: Wait for DNS propagation

  • Changes take 24-48 hours to fully propagate
  • Wait 2 days, then re-check

Check 2: Syntax error

  • Go to mxtoolbox.com and look for the error message
  • If it says "Invalid syntax," your SPF record has a typo
  • Correct the record in your domain registrar

Check 3: Mixed flattened and non-flattened

  • Don't mix IP lists and includes in one record (causes confusion)
  • Either flatten everything or use includes, not both

Check 4: Wrong domain

  • Make sure you're checking the right domain
  • If using subdomain (mail.yourdomain.com), check that domain, not main domain

FAQ

Q: How many lookups is acceptable?

A: Under 10. Ideally under 8 (gives you headroom to add 1-2 more services later).

Q: Do all ISPs enforce the 10-lookup limit?

A: Yes. It's in the SPF specification. Every ISP that checks SPF respects this limit.

Q: If I flatten SPF, do I still need regular updates?

A: Yes. When email services add new sending IPs (e.g., new data center), you update your SPF with new IPs. Your domain host handles this.

Q: Is SPF flattening permanent or temporary?

A: Permanent. Once flattened, you maintain the flattened record. You can unflatten it later if you want.

Q: What if I use an email service that doesn't publish IPs?

A: They should include instructions. If they don't, contact their support. All legitimate email services provide SPF includes or flattened IP lists.

Q: Can I use a subdomain for SPF to avoid the limit?

A: Yes. Use mail.yourdomain.com with its own SPF. You'll have main domain SPF + mail subdomain SPF (separate records, separate lookup limits).

Next Steps

  1. Check your SPF at mxtoolbox.com right now
  2. Note the lookup count
  3. If 10 or below: You're fine, no action needed
  4. If above 10:
  • Identify unused email services in your SPF
  • Remove 2-3 unused ones
  • Wait 24-48 hours
  • Re-check at mxtoolbox.com
  1. If still above 10:
  • Contact your domain registrar
  • Request SPF flattening
  • They'll handle consolidating IPs
  1. Once under 10: SPF should pass and emails should stop bouncing

Most clients fix SPF lookup issues in 1-2 weeks by removing unused services.

If you're using 50+ domains or highly complex infrastructure, professional setup is worth it.

Check our packages: https://imisofts.com/cold-email-marketing#packages

Read next: DMARC Failing Fix | SPF DKIM DMARC Setup | Email Deliverability

Frequently Asked Questions

Under 10. Ideally under 8 (gives you headroom to add 1-2 more services later).
Yes. It's in the SPF specification. Every ISP that checks SPF respects this limit.
Yes. When email services add new sending IPs (e.g., new data center), you update your SPF with new IPs. Your domain host handles this.
Permanent. Once flattened, you maintain the flattened record. You can unflatten it later if you want.
They should include instructions. If they don't, contact their support. All legitimate email services provide SPF includes or flattened IP lists.

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