What Is SPF and Why Does It Matter?
SPF (Sender Policy Framework) is your domain's way of saying "these servers are authorized to send email on my behalf." It's a DNS record that receiving mail servers check before accepting messages claiming to be from your domain.
Without SPF, anyone can send email that looks like it comes from you. Spammers, phishers, and attackers exploit this constantly. SPF helps receiving servers distinguish your legitimate email from forgeries-improving your deliverability while protecting your domain reputation.
How to Check SPF Records
Looking up SPF records is straightforward:
- Enter the domain name (e.g., example.com) in the input field
- For multiple domains, add one per line
- Click Lookup to query DNS records
- Review the SPF record and parsed results
- Check for errors or configuration issues
Understanding SPF Syntax
SPF records follow a specific format. Here's what the components mean:
Version Identifier
Every SPF record starts with v=spf1. This tells receiving servers it's an SPF record (version 1). There's no SPF version 2-this identifier has been standard since SPF's creation.
Mechanisms
Mechanisms define what's authorized:
- ip4:192.168.1.1 - Authorize a specific IPv4 address
- ip4:192.168.1.0/24 - Authorize an IP range (CIDR notation)
- ip6:2001:db8::1 - Authorize an IPv6 address
- include:_spf.google.com - Include another domain's SPF record
- a - Authorize the domain's A record IP
- mx - Authorize the domain's MX record IPs
- ptr - Authorize by reverse DNS (deprecated, avoid using)
Qualifiers
Qualifiers appear before mechanisms to specify the result:
- + (Pass): Authorized (default if no qualifier)
- - (Fail): Not authorized, reject the message
- ~ (SoftFail): Not authorized but don't outright reject
- ? (Neutral): No opinion, treat as if no SPF
The All Mechanism
Every SPF record should end with an "all" mechanism that specifies the default policy:
- -all: Reject mail from non-listed servers (strictest, recommended)
- ~all: Soft fail-accept but mark as suspicious (common during rollout)
- ?all: Neutral-no policy for unlisted servers (not recommended)
- +all: Pass everything (dangerous, defeats SPF's purpose)
Common SPF Configurations
Google Workspace (Gmail)
If you use Google Workspace for email:
v=spf1 include:_spf.google.com -all
This authorizes Google's mail servers and rejects everything else.
Microsoft 365
For Microsoft 365 email:
v=spf1 include:spf.protection.outlook.com -all
Multiple Services
Using multiple email services? Combine them:
v=spf1 include:_spf.google.com include:sendgrid.net ip4:203.0.113.5 -all
This authorizes Google, SendGrid, and a specific IP address.
Common SPF Problems
Too Many DNS Lookups
SPF allows maximum 10 DNS lookups. Each "include:" and similar mechanism counts. Exceeding this limit causes SPF to fail. Solutions:
- Replace includes with direct IP addresses where possible
- Remove unused services from SPF
- Use SPF flattening services for complex records
Multiple SPF Records
Domains can only have one SPF record. Multiple records cause lookup failures. If you find duplicates, merge them into a single record with all necessary mechanisms.
Missing SPF Record
No SPF record means no email authentication via SPF. Receiving servers can't verify your senders, potentially hurting deliverability. Add an SPF record if you send email from the domain.
SPF and Email Deliverability
Properly configured SPF directly impacts whether your email reaches inboxes:
- Major email providers (Gmail, Outlook, Yahoo) check SPF
- Failed SPF checks increase spam score or trigger rejection
- Consistent SPF passes build positive sender reputation
- SPF alignment with DMARC enables stricter authentication policies
If you're having deliverability issues, checking your SPF configuration is an essential first step.
Batch Domain Checking
Managing multiple domains? Our tool handles batch lookups:
- Enter multiple domains, one per line
- Process hundreds of domains in one query
- Results show SPF status for each domain
- Quickly identify domains missing SPF or with errors
This is valuable for IT teams managing domain portfolios, agencies handling client domains, or anyone auditing email authentication across many domains.
Frequently Asked Questions
What is an SPF record?
SPF (Sender Policy Framework) is a DNS TXT record that specifies which mail servers are authorized to send email for your domain. When receiving servers check SPF, they verify the sending server is on your authorized list, helping prevent email spoofing.
Why is SPF important for email deliverability?
Without SPF, anyone can send email pretending to be from your domain. Receiving servers use SPF to verify sender legitimacy. Properly configured SPF improves deliverability because your legitimate emails are less likely to be flagged as spam or rejected.
How do I read an SPF record?
SPF records start with 'v=spf1' and contain mechanisms like 'ip4:' (allowed IP addresses), 'include:' (authorized third-party senders), 'a' (domain's A record), 'mx' (domain's mail servers), and end with 'all' (policy for non-matching senders, typically '-all' to reject or '~all' for soft fail).
What does 'SPF record not found' mean?
The domain has no SPF record configured. This means no email authentication via SPF, making the domain vulnerable to spoofing and potentially hurting email deliverability. If you own the domain, you should add an SPF record to your DNS.
Can a domain have multiple SPF records?
No. Having multiple SPF records is invalid and causes SPF checks to fail. If you need to authorize multiple services, combine them into a single SPF record using 'include:' mechanisms. Many domains accidentally create duplicates when adding new email services.