Why does SPF misconfiguration cause the 553 5.1.3 error?

You sent an email. It bounced. The error code? 553 5.1.3. You checked the address. It was correct. The content was clean. The sender domain looked right. So why was it blocked?

The answer lies in SPF—the email authentication method buried deep in your DNS settings. When your mail server’s IP isn’t listed in the domain’s SPF record, the receiving server sees the message as unauthorized, even if you’re not a spammer.

SPF works like a digital gatekeeper. It tells incoming mail servers, “Only these IPs can send email for this domain.” If your server’s IP isn’t on the list, the gate stays closed. That’s exactly what triggers the 553 5.1.3 error: the sender’s IP is rejected because it’s not authorized in the SPF record.

Key takeaways

  • The 553 5.1.3 error occurs when the sender's IP address is not included in the domain's SPF record.
  • SPF is a DNS-based email authentication method that defines which IP addresses are allowed to send mail for a domain.
  • Even legitimate emails are blocked if the sending IP is missing from the SPF record, causing delivery failure.

What does the 553 5.1.3 SMTP error actually mean?

The 553 5.1.3 SMTP error means the receiving mail server rejected your message because it couldn’t verify your sender address or authentication. It’s not about spam, content, or formatting — it’s a technical failure in sender validation, often caused by misconfigured SPF, DKIM, or incorrect sending IPs. This happens most often when setting up mail through an ESP or custom SMTP, especially after domain moves or server updates.

Why authentication fails — beyond just the error code

When you see 553 5.1.3, the server isn’t saying your email is bad — it’s saying your identity can’t be confirmed. The receiving system checks your domain's SPF record to see which servers are authorized to send on its behalf. If your sending IP isn’t included in that record, the server blocks the message outright. It’s a security gate, not a content filter.

Let’s say you've migrated your email service or changed your mail server. If the new IP address isn’t added to your SPF record, every message sent from it will trigger this error. This is especially common with ESPs like SendGrid or AWS SES when you’re using a custom domain. Even a single missing IP can cause failures across your email deliverability.

SPF records are not just checks — they’re a foundation of email trust. A malformed or incomplete SPF record can result in a failure like 553 5.1.3, even if the email content is perfect. It’s not your writing, it’s who’s sending it — and that identity must be verifiable.

How to fix it in practice

First, verify your SPF record using tools like MxToolbox or the SPF specification (RFC 7208). Check that the sending IP address of your mail server is explicitly listed. If you use multiple services, you must include all authorized IPs. A common mistake is relying on a single SPF record without updating for new infrastructure.

Overly long SPF records can also cause issues — the limit is 10 DNS lookups. If you exceed it, some servers reject the email without warning. Use tools like SPFCheck.org to validate your configuration.

Before you send mass emails, run inbox placement testing to confirm SPF and related authentication are properly enforced. You can also use real-time email verification to check if sender domains and IPs are aligned with their published records. Verify your sender infrastructure with precise checks that include domain and IP legitimacy.

Is your SPF record incomplete? How to verify it

Yes, if your SPF record doesn’t include the exact IP address of your sending mail server or ESP, mail providers will reject your messages with a 553 5.1.3 error. Even a single missing IP or a malformed include directive can derail delivery. Let’s check your record step by step.

Check your SPF record using a DNS lookup tool

  • Use a tool like MXToolbox or the command-line dig to retrieve your domain’s TXT records.
  • Look for the record that starts with v=spf1—this is your SPF policy.
  • Make sure it’s the only SPF record for your domain; multiple records cause validation failure.

Verify the record's content and structure

  • Confirm your sending mail server IP (like 192.0.2.1) is listed exactly—no ranges, no typos.
  • Check that any include: directives point to valid, active SPF policies (e.g., include:spf.protection.outlook.com).
  • Ensure you haven’t exceeded the 10 DNS lookup limit—each include, redirect, or mx counts as one.
  • Avoid duplicate mechanisms like multiple ip4: or include: without consolidation.
  • If you use an ESP (like SendGrid or Mailchimp), use their official SPF instructions to ensure the right IP is included.
Even a single misconfigured include directive can invalidate your entire SPF record—don’t rely on assumptions.

Common issues include omitting required IPs, using outdated or incorrect include tags, or combining multiple SPF records. These errors trigger the 553 5.1.3 error you're seeing. Once corrected, it can take 24–48 hours for DNS caches to update globally.

When in doubt, verify your full DNS setup with a tool like RFC 7208, the official SPF specification. It outlines strict rules about parsing, mechanism order, and lookup limits.

If you’re verifying a large list of sender domains or want to ensure all email infrastructure aligns with best practices, consider using a real-time verification tool to audit your sending setup before deployment. You can test and validate records in bulk with bulk email list cleaning to catch issues before they hit deliverability.

The full 553 5.1.3 SPF fix: step-by-step

If your mail server IP isn't in your SPF record, email providers return a 553 5.1.3 error because they reject messages from unapproved sources. Fix it by updating your DNS TXT record to include your sending IP or your ESP’s SPF include directive, then verify propagation and test delivery. The fix is exact—but the result matters: inbox delivery.

Step-by-step DNS adjustment

  1. You must access your domain’s DNS settings through your registrar (like GoDaddy) or DNS provider (like Cloudflare or AWS Route 53). This is where email authentication is managed, not your email service.
  2. Look for the existing SPF TXT record, usually labeled @ or your domain name. It may begin with v=spf1. If multiple SPF records exist, you have a critical flaw—only one is allowed.
  3. Check whether your mail server’s IP (e.g., ip4:192.0.2.1) is listed. If not, the record is incomplete. Many senders using third-party services like SendGrid or Amazon SES don’t know their IP must be included or properly referenced.
  4. If missing, edit the record to add the IP or use include:_spf.sendgrid.net (replace with your ESP’s published SPF). This is the standard, reliable method. Never use include:spf.yourdomain.com unless you control that domain.
  5. Save the change. DNS updates take 5–15 minutes to propagate, though some networks may cache longer. Do not assume it's live immediately.
  6. Verify the update with a DNS checker tool—use MxToolbox or RFC 7208 to validate syntax. A malformed record worsens deliverability than no SPF at all.

Test after correction

After propagation, send a test email to a known inbox. Use a service like inbox placement testing to confirm delivery and check spam scores. If the 553 5.1.3 error persists, validate that no old SPF records remain in DNS, or run a header analysis to see where the rejection occurs.

SPF is strict—you can’t have multiple records. Use just one, clearly defined, and keep it updated. If your ESP changes IPs, you’ll need to update the include or IP list accordingly. Automated tools help—like bulk email list cleaning software that checks sender alignment and domain health before sending.

Common SPF configuration mistakes that trigger 553 5.1.3

SPF errors like 553 5.1.3 often stem from misconfigured DNS records—primarily when you have multiple SPF records, use incorrect include directives, or fail to validate IPs listed in your record. The most common root cause? Only one SPF TXT record is allowed per domain; adding a second one breaks authentication and triggers rejection.

Multiple SPF records are not supported

You might think stacking SPF records helps, but DNS only allows one SPF TXT record per domain. If you’ve added a second one—whether via a misconfigured email service or a legacy tool—it invalidates the entire SPF. This is a hard rule defined in RFC 7208, not a suggestion.

Let’s say you use both your hosting provider and your ESP to set SPF entries. That’s a conflict. The receiving server sees multiple TXT records and can’t determine which one to trust, so it rejects your message. Always collapse all SPF settings into a single record using include: or ip4: directives.

Using someone else's SPF or outdated includes

It’s tempting to copy an SPF record from a former ESP or a template. But if you’re not managing the domain that owns the record, you’re risking a 553 5.1.3 bounce. For example, an include:sendgrid.net directive works only if SendGrid has explicitly authorized you to use it—and only if their SPF record hasn’t changed.

Many legacy include directives are outdated. If you’re still using a record tied to a discontinued service, it may no longer be valid or may have been removed altogether. This causes SPF failures even if your IP is otherwise legitimate.

Another common slip: adding a send-only mail server IP without confirming it’s in the SPF record. Even one missing IP can break alignment if the receiving server checks the sending IP against the SPF domain. It doesn’t matter if it’s correct in your email client—it must match DNS.

SPF is a critical part of sender reputation. A single misconfigured include or duplicate record can cost you inbox placement. Use tools like MxToolbox or RFC 7208 to validate your setup before sending. For a deeper check, run a full DNS audit of your domain's SPF, DKIM, and DMARC configuration.

If you're unsure whether your list is clean or your SPF is configured properly, run a bulk verification to spot invalid emails before sending, which helps maintain deliverability health.

How to prevent SPF errors before they cause bounces

If your SPF record doesn’t include the correct mail server IP, messages will be rejected with error 553 5.1.3. This happens when the sending IP isn’t listed in your domain’s SPF policy. Prevent it by auditing records regularly, using automated tools to check consistency, and never assuming third-party providers configure SPF correctly for your domain. Keep a live inventory of all sending IPs across your network and update SPF as changes occur.

Start with a proactive audit process

  • Review your SPF record every time you switch email providers, add new sending services, or update infrastructure.
  • Use tools like RFC 7208 to verify your record follows current standards — limits of 10 DNS lookups per SPF check are strictly enforced.
  • Look for common mistakes: overuse of include directives, missing ~all or -all mechanisms, or outdated IPs.

Automate consistency checks

  • Deploy automated DNS validation tools that scan for SPF syntax issues and policy misalignments across your domains.
  • Let’s say you use Mailchimp for campaigns and SendGrid for transactional mail — their IPs will differ. You’re responsible for including both, unless you’re using a unified platform with a known shared IP pool.
  • Never assume an email service provider’s SPF settings are automatically correct for your domain — they may list their own IPs but not your domain’s record.
  • Track every sending IP across your network and maintain a central log, updated in real time when configurations change.

Even a single missing IP in SPF can cause delivery failure. Regular checks reduce the risk. Tools like bulk email list cleaning can help identify misrouted or stale addresses, but SPF validity is a sender-side configuration issue you need to manage directly. Treat SPF as dynamic — it evolves with your infrastructure. A minor oversight today can trigger mass bounces tomorrow.

SPF, DKIM, and DMARC: their roles in sender reputation

You can’t build or maintain sender reputation without SPF, DKIM, and DMARC working together. SPF checks if the sending server’s IP is authorized; DKIM cryptographically signs the email to prevent tampering; DMARC ties them together, enforcing policies when either check fails. Together, they’re the foundation of email trust and deliverability.

SPF: the sender’s IP authorization

SPF is your first checkpoint: it verifies whether the email came from an IP address authorized to send on your domain’s behalf. If your SPF record doesn’t list the mail server’s IP — say, 192.0.2.1 — the email will fail SPF, and inbox providers treat that as a red flag. This is why a 553 5.1.3 error often means SPF is misconfigured.

Many organizations use third-party services like SendGrid, Mailchimp, or Amazon SES to send emails. If those providers aren’t explicitly listed in your SPF record, your messages won't pass. Adding them correctly is essential — but overloading the record with too many mechanisms can cause issues. The SPF specification caps at 10 DNS lookups, so be strategic.

DKIM: ensuring message integrity

While SPF focuses on the sender’s identity, DKIM ensures the message hasn’t been altered in transit. When you sign an email with DKIM, a unique cryptographic hash is added to the headers. Recipients validate this hash against your public key in DNS, confirming the content matches what was sent.

Even if SPF passes, a failed DKIM check signals tampering — which could mean a message was intercepted or modified. This triggers suspicion and impacts sender reputation. Unlike SPF, DKIM doesn’t block delivery outright, but repeated failures degrade trust over time.

DMARC: enforcing policy with accountability

DMARC is the policy layer that ties SPF and DKIM together. You set a DMARC record that says: “Only accept emails that pass SPF OR DKIM. If neither passes, quarantine or reject.” You can also request feedback reports (RUA and RUF) to see what’s failing and why.

DMARC is critical for preventing spoofing and protecting your domain reputation. Without it, attackers can impersonate you — even if your SPF and DKIM are set up correctly. According to a DMARC specification RFC, it’s an industry-standard requirement for high-volume senders.

Let’s be practical: if you're seeing 553 5.1.3 errors, start with SPF. A correctly configured SPF record listing all allowed IPs — including those from your email service provider — is the first step. You can test your setup with tools like MXToolbox. Once SPF is solid, move to DKIM and DMARC.

For ongoing list hygiene and sender alignment, verify your email addresses in bulk — ensure only valid, deliverable addresses are in your campaigns. Clean your mailing list regularly to avoid sending to invalid or high-risk addresses.

Using Email List Validation to prevent deliverability issues

If your SPF record isn’t including your mail server’s IP and you’re getting a 553 5.1.3 error, it’s likely because the recipient’s mail server rejected your message due to failed authentication. You can fix this by validating your sending setup and cleaning your email list before sending. Using Email List Validation’s inbox-placement testing, real-time API, and bulk verification tools helps you catch and resolve issues like missing SPF records, outdated DNS settings, and poor sender reputation before they hurt deliverability.

Verify sender alignment and list quality proactively

  • Use inbox-placement testing to simulate real-world delivery against major providers (Gmail, Outlook, etc.) and identify whether your SPF, DKIM, or DMARC configurations are failing.
  • Run your list through Email List Validation’s real-time verification API to detect invalid addresses, catch-all domains, and misconfigured mail servers—common causes of 553 5.1.3 errors.
  • Perform bulk list verification to flag and remove emails that may harm sender reputation, including disposable addresses, role accounts, or addresses with known deliverability issues.
  • Ensure your ESP (like SendGrid, Mailchimp, or Klaviyo) is properly authenticated by validating your setup with Email List Validation’s integrations, which check for SPF alignment and other authentication flaws before delivery.

Align technical setup with list hygiene

Authentication doesn’t just matter in theory. The SPF record must include your actual outbound mail server IP—otherwise, even properly formatted messages are rejected. Let’s say your mail server runs on 192.0.2.100 but your SPF record only lists 192.0.2.101. That mismatch triggers a 553 5.1.3 error at the receiving end. This isn’t a one-off fix. It requires repeated verification of both your DNS configuration and your sending list.

Tools like Email List Validation don’t just flag problems—they help you act before damage occurs. You’re not just catching bad addresses; you’re testing how your entire sending stack performs in real conditions. According to RFC 5321, the SMTP protocol requires clear sender authentication. When SPF alignment fails, servers reject the message. Tools that validate both technical setup and list quality keep you compliant and reduce bounce rates.

Can SPF alone fix the 553 5.1.3 error?

You might think a properly configured SPF record will fix the 553 5.1.3 error, but it’s not that simple. This error specifically points to an SPF failure — usually because the sending IP isn’t authorized in the recipient’s SPF policy. However, even with correct SPF, your email can still be rejected if DKIM isn’t aligned or DMARC is misconfigured. Authentication is a stack, not a single layer.

SPF is just one piece of the puzzle

Let’s be clear: SPF alone can’t guarantee inbox placement. The 553 5.1.3 error is SMTP code for a sender policy rejection, but other failures — like DKIM signature mismatches or DMARC alignment issues — trigger different responses, often with similar outcomes: bounce, quarantine, or hard rejection.

For example, a message might pass SPF but fail DMARC if the “from” domain in the header doesn’t align with the domain used in the DKIM signature. That misalignment leads to rejection, even if the sender IP is valid. It’s not the SPF record that’s broken — it’s the overall alignment of multiple authentication mechanisms.

Why a full authentication stack matters

Industry standards — like those from the Messaging, Malware, and Mobile Anti-Abuse Working Group (M3AAWG) — emphasize that consistent use of SPF, DKIM, and DMARC is how senders prove identity and reduce abuse. Relying only on SPF leaves you vulnerable to spoofing and increases the chance of delivery failure.

Even if you fix SPF to include your mail server’s IP, the absence of a valid DKIM signature or lack of DMARC enforcement can still result in your email being marked as suspicious. This is especially true with large providers like Gmail and Outlook, which use advanced filtering based on multiple signals.

It’s not just about avoiding one error code — it’s about building a reputation. Email services track sender behavior, authentication compliance, spam complaints, and engagement. A single flawed layer in your stack undermines the whole process.

Use tools that validate all layers, not just SPF. Email List Validation’s bulk verification helps identify invalid addresses and catch-all domains, which can indirectly affect alignment and sender reputation.

Learn more about how to audit your authentication stack and reduce bounces: clean your email list and improve deliverability.

What happens if you ignore the 553 5.1.3 error?

If you ignore the 553 5.1.3 error—caused by an SPF record that doesn't include your mail server's IP—you’re blocking emails before they even reach the inbox. Messages fail on the first hop, leading to immediate delivery failure, degraded sender reputation, and eventually, domain-level blocking. Let’s break down what happens when you don’t fix it.

Immediate consequences of neglecting 553 5.1.3

  • Every email sent from your domain fails at the receiving server’s first check—before bounce handling or spam filtering even applies.
  • Delivery failure rates spike to near 100% for messages sent from unlisted IPs, meaning your campaigns, alerts, and transactional emails never arrive.
  • Spam filters like those used by Gmail, Outlook, or Yahoo observe repeated failures and may flag your domain as unreliable, even if your content is clean.

Long-term damage to sender reputation and domain health

  • Over time, consistent SPF failures signal poor email hygiene. Major email providers use sender reputation as a core part of inbox placement decisions.
  • Even if the same domain sends legitimate content later with correct SPF, reputation systems may still block inbound messages due to past misconfigurations.
  • Eventually, mail servers may block your domain entirely without warning—especially if your IP is flagged or your domain appears on blocklists like Spamhaus, which tracks repeated policy violations.
  • Recovery is difficult: it can take days to weeks, even with corrections, if the domain has been marked as suspicious.

SPF is not a luxury—it’s a foundational gatekeeper. When misconfigured, it acts like a locked front door. A single missing IP in your SPF record can shut down all outbound email.

As noted by the Internet Engineering Task Force (IETF), SPF validation is a standard part of email acceptance procedures. Skipping it can result in automatic rejection. See the official specification at RFC 7208.

You don’t need to fix just one email—fixing SPF ensures all your outbound mail, from newsletters to payment receipts, can reach inboxes reliably.

If you're unsure which IPs should be in your SPF record, use a full-featured email validation tool to audit your domains and check for policy gaps. Real-time SPF validation helps catch errors before they impact delivery.

Clean your entire list with bulk email validation to catch not just SPF issues, but also invalid addresses, role accounts, and disposable domains—all of which degrade deliverability.

Final check: is your domain ready for sending?

Your SPF record must include the IP address of every mail server that sends email on your domain’s behalf. Omitting even one can trigger a 553 5.1.3 error, blocking delivery.

After any change to your DNS records, test immediately using tools that simulate real-world sending. Only then can you trust that your setup works across providers and inbox filters.

Verify before you send

  • Use Email List Validation’s deliverability testing to check inbox placement across major providers before large campaigns.
  • Keep SPF, DKIM, and DMARC records in sync and documented—misalignment breaks authentication.
  • Regular testing confirms your domain remains in good standing with receiving mail servers.

Keep reading

Ready to put this into practice? Email List Validation verifies emails with 98.9% accuracy — start with 100 free verifications.

Frequently asked questions

How do I find my mail server IP for SPF?

Check your email service provider’s documentation or contact support. For SendGrid, it’s in the SMTP settings. For on-premise servers, use your network IP or public-facing address.

Can I use multiple include statements in SPF?

Yes, but only if they don’t exceed the 10 DNS lookup limit. Too many includes can cause SPF validation to fail.

Is it safe to set SPF to -all?

Yes, as long as all authorized sending IPs are included. -all means reject all unlisted IPs — it’s a strict policy for security.

Does SPF affect email spam scores?

Yes. Missing or incorrect SPF increases the risk of email being marked as spam or blocked by receivers.

What if my ESP changed their IP without me knowing?

Monitor your SPF and DNS records regularly. Use email verification tools to detect delivery issues early.

How long does SPF propagation take?

DNS changes usually propagate within 5 to 15 minutes. Some networks may take up to 24 hours to fully update.

Can I have SPF and DMARC at the same time?

Yes — DMARC relies on SPF and DKIM for validation. They work together to enforce sender policies and improve inbox placement.

Why does my test email fail after fixing SPF?

DKIM or DMARC misconfiguration could still be blocking delivery. Check both after fixing SPF.

Does Email List Validation fix SPF?

It doesn’t edit DNS records directly, but it checks SPF compatibility during verification and delivers deliverability test reports.

Are disposable email addresses affected by SPF?

No — SPF applies only to sending infrastructure. Disposable domains are filtered through other checks like domain reputation and role addresses.

Can a valid SPF record cause a 553 5.1.3 error?

Only if the sending IP is not authorized. A valid record still blocks unknown IPs, even if they are correct on paper.

Should I use v=spf1 or spf1 in DNS?

Always use v=spf1 as the version tag. Missing the 'v=' prefix can cause the record to be ignored.