It is crucial for your emails to land in your recipients' inboxes. Verifying your domain's SPF (Sender Policy Framework) record plays a big part in this. SPF records specify which mail servers are authorized to send emails on behalf of a domain, helping to prevent spoofing and improve email deliverability.

When you run an SPF check, you’ll see one of these results:

• SPF pass: Your record is correctly set up. No action needed.
• No SPF record found: Your domain lacks an SPF record, increasing the risk of emails being flagged. Add an SPF record in your DNS settings.
• Syntax error: Formatting issues in your SPF record may disrupt email delivery. Check for typos, missing characters, or incorrect syntax.
• Too many DNS lookups: SPF records allow a maximum of 10 lookups. Exceeding this limit may cause failures—reduce unnecessary include statements.
• Multiple SPF records found: Having more than one SPF record causes authentication failures. Merge them into a single entry.

Each result helps diagnose SPF issues and improve email deliverability.

Common SPF errors and how to fix them

SPF records help authenticate emails, but common issues can cause failures:

• Too many DNS lookups: SPF allows up to 10 lookups; exceeding this limit may cause mail servers to ignore your record. Reduce unnecessary include statements or use SPF flattening to consolidate entries.
• Syntax errors: A missing space, extra character, or incorrect formatting can break your SPF record. Use an SPF validator to identify and correct mistakes.
• Multiple SPF records: Having more than one SPF record invalidates authentication. Merge all unique include, IP4, and IP6 mechanisms into a single entry, starting with v=spf1 and ending with ~all or -all.

Keeping your SPF record clean, formatted correctly, and within lookup limits ensures better email deliverability and security.

SPF alone isn't enough if you manage multiple domains, work with different email service providers, or want to maximize email deliverability. You need a solid strategy. Below are four key best practices to help you avoid conflicts, maintain accuracy, and strengthen your email authentication setup.

Manage multiple senders in a single SPF record

If you use multiple email service providers (ESPs) to send emails from your domain, your SPF record needs to include all authorized senders without exceeding the DNS lookup limit. Mismanaging this can lead to conflicts, causing emails to be rejected or marked as spam.

Reducing DNS lookups with SPF flattening:

SPF has a limit of 10 DNS queries, and exceeding this limit can break authentication. If your record has too many include statements, SPF flattening helps reduce lookups. This process replaces include mechanisms with a single list of IP addresses, condensing multiple lookups into one.

To flatten your SPF record:

1. Use an SPF lookup tool to extract the actual IP addresses behind include statements.
2. Replace the include mechanisms with these IP addresses in your SPF record.
3. Some ESPs offer pre-flattened SPF records or tools that automate this process—check with your provider for recommendations.

Proactive SPF monitoring and maintenance

SPF records aren’t a one-time setup—they need regular updates (we’re talking quarterly) to maintain email deliverability as you add new email services or make domain changes.

How to conduct routine SPF checks:

• Monitor new sending sources: Ensure new ESPs and marketing platforms are included in your SPF record.
• Track domain changes: If you update hosting or switch domains, verify your SPF record still points to the correct mail servers.
• Check SPF for errors: Regularly run SPF checks to catch syntax mistakes, outdated entries, or conflicting settings.

Some platforms, like ActiveCampaign, provide SPF monitoring to alert you of issues, while third-party tools can automate scans and notify you of discrepancies.

Combine SPF with DKIM and DMARC for maximum security

Setting up DKIM and DMARC alongside SPF is like adding extra locks to your email security door. While SPF checks that emails come from the right servers, DKIM adds a digital signature to make sure the email hasn’t been changed on its way. Then, the DMARC record steps in to enforce your rules and report suspicious behavior, helping to stop phishing and spoofing.

The three work together to keep your emails safe, ensure they reach inboxes, and protect your domain from being misused.

Handling errors despite a valid SPF record

Even with a solid SPF record, emails can still get blocked or flagged as spam. This might happen if there are issues with DNS propagation, if hosting settings conflict with your SPF record, or if your domain has a poor reputation.

Troubleshooting blocked or flagged emails

Start by verifying DNS propagation. This can take up to 48 hours to spread across the internet, so make sure your SPF record is fully updated. Next, re-check your hosting settings to ensure no conflicting DNS records override your SPF setup. If the problem persists, the domain owner should use advanced deliverability tools to analyze email headers, check blocklists, and assess their sending reputation.

SPF plays a key role in helping email providers verify whether an email message is coming from an authorized source or a spoofed sender. When an email is sent, providers check the SPF record to verify that the sending server is authorized to send emails for that domain. If the SPF check fails, the email is more likely to be flagged as suspicious or rejected outright, helping prevent phishing and impersonation.

A misconfigured SPF record can weaken security, increasing the risk of email spoofing and lowering deliverability rates. If email providers can't authenticate your messages, they may land in the spam folder, leading to lower open rates, click-through rates, and potentially damaging your brand's credibility. A poorly set up SPF record signals to recipients that your email practices might not be trustworthy.

On the flip side, proper SPF setup contributes to a unified authentication system when paired with DKIM and DMARC. This trio of security protocols ensures your emails are legit, improving deliverability and protecting your brand's reputation while reducing the chances of fraud or spoofing.

SPF is a key step in ensuring your emails are properly authenticated, which means they’re more likely to land in the right inbox instead of the spam folder. This allows you to run more effective, personalized campaigns because your audience is actually seeing your messages. When your emails pass SPF checks, they’re trusted by email providers, giving you a better chance to connect with subscribers.
With ActiveCampaign, you can ensure your SPF record is set up correctly for secure and reliable email delivery and gain access to powerful tools for creating and managing targeted campaigns.

• ActiveCampaign’s advanced segmentation allows you to tailor your messages based on user behavior, demographics, and past interactions.
• You can set up automated workflows to trigger personalized emails at the right time, boosting engagement.
• Plus, in-depth reporting helps you track performance, optimize content, and fine-tune your targeting to ensure you’re reaching the right inbox with content your audience cares about.

Lingering questions? Let’s cover a few.

What happens if I have multiple SPF records for one domain?

Email servers can’t process multiple SPF records, leading to authentication failures. Merge all ‘include’ mechanisms, IP addresses, and SPF elements into a single record, starting with v=spf1 and ending with ~all or -all.

How can I resolve a DNS lookup limit error?

SPF allows up to 10 lookups—exceeding this limit may cause failures. Use SPF flattening to replace include mechanisms with a direct list of IP addresses, and remove unnecessary entries to stay within limits.

What should I do if my SPF record is correct but emails still bounce?

Check if DKIM and DMARC are set up, as SPF alone may not prevent bounces. Also, verify that your sending IP isn’t on a blocklist and conduct a deliverability audit to identify issues.

Callout: ActiveCampaign offers deliverability consultations to review your current strategy, goals, and business details. Then, we’ll help you put together an actionable plan to achieve the results you want.

How frequently should I check and update my SPF record?

Review your SPF record at least quarterly or whenever you add a new email provider, update hosting, or change DNS settings to keep authentication accurate.

What are some common SPF authentication mechanisms?

Common SPF authentication mechanisms include:

• IP addresses (IP4 / IP6): Specifies which IPs can send emails for your domain. Ideal for self-hosted servers or known sending IPs.
• Hostnames (a, mx): Uses the domain’s A record (IP address) or MX records (mail servers) for authentication. Useful for dynamically assigned mail servers.
• include: Adds third-party ESPs (e.g., Mailchimp, ActiveCampaign) to your SPF record for authentication.

Should I use "~all" or "-all" at the end of my SPF record?

The choice between ~all and -all at the end of your SPF record depends on how strictly you want to enforce authentication.

• ~all (SoftFail): Flags unauthorized emails as suspicious but still delivers them (best for testing).
• -all (Fail): Blocks unauthorized emails entirely (best for strict security).

In general, start with ~all for testing and then switch to -all once you're sure your SPF setup is correct and you want to enforce stricter authentication.

How do I add a new third-party sending service to my SPF record?

To add a new third-party sending service to your SPF record, follow these steps:

1. Find the provider’s SPF entry (e.g., include:spf.provider.com).
2. Edit your SPF record to add it alongside existing mechanisms.
3. Verify the record to ensure syntax is correct and stays within the 10 lookup limit.

It’s crucial to stay within the 10 DNS lookup limit to ensure the SPF record remains valid and email authentication works correctly.

What's the difference between hard SPF fails and soft SPF fails?

A hard SPF fail (-all) blocks emails from unauthorized sources, while a soft SPF fail (~all) allows them but marks them as suspicious, often sending them to spam instead of rejecting them outright.

Learn more: Why ActiveCampaign is a leader in deliverability