SPF and DMARC: The Key DNS Records for Reliable Email Deliverability

Even sincere business emails can find themselves lost in spam folders or rejected entirely if your domain isn't correctly authenticated in today's email environment. DNS records like SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting and Conformance) become especially important here. These email authentication methods guarantee that you are who you say you are as a sender, therefore preventing spammers and fraudsters from copying your domain. Major email providers increasingly demand such authentication; as of 2024, businesses including Google, Yahoo, and Microsoft have policies like DMARC for senders. Along with DKIM, DomainKeys Identified Mail, successfully integrating SPF and DMARC offers a framework to verify your emails, raise deliverability, and guard your domain against abuse. Common mistakes to avoid, practical measures to guarantee your emails reliably reach their recipients, what SPF and DMARC are, why they matter, and how they assist when utilizing your own servers and third-party platforms (Mailchimp, CRM tools, invoice software, etc. ), will all be discussed in this article.

What is SPF (Sender Policy Framework)?

Basically a DNS TXT record, SPF specifies every mail server allowed to send email for your domain. Consider it to be a "allowed senders" list for your domain. The receiving mail server examines the SPF record of your domain to determine if the sender's IP address is on that list every time an email purportedly from your domain is received. SPF passes if the IP is allowed; otherwise SPF fails and the message could be rejected or flagged. This basic mechanism lets receiving mail systems confirm the authenticity of the sender.

An example SPF record might look like:

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

In this case, v=spf1 indicates the record is SPF; include:_spf. google. com is meant to denote "also trust servers listed in Google's SPF record" (usual for Google Workspace senders); and ~all is a soft fail for any sender not on the list (hence unauthorized senders should be flagged as suspicious). A more stringent choice is -all, telling receivers to reject any non-listed senders.

SPF for several services: Many businesses use several email sending tools, maybe one employing a mail marketing platform (like Constant Contact or Mailchimp) plus a distinct automation system (like Klaviyo) and perhaps their own mail server. It is crucial to combine all authorized senders into one SPF record. Publishing several SPF TXT records for the same domain—having more than one will generate mistakes—should not be done. Include every required server or domain in a single record rather. For instance, your SPF record should have include: statements for two providers. This guarantees that any server legally acting on your behalf is identified and will pass SPF testing. Ignoring all valid mail sources can cause SPF "fail" outcomes and later email rejections.

SPF and Email Delivery: Using SPF properly improves your reputation with recipients' email servers. One sign the email is not counterfeit is SPF passes. Many inbox providers would question the message if SPF fails and it is not otherwise certified—perhaps rerouting it to spam or refusing it. Emails can fail these tests as a result of misconfigured SPF (i. e. , syntax mistakes, missing entries, or exceeding DNS lookup restrictions), therefore compromising delivery and opening your domain to spoofing abuse. Essentially, a good SPF record is a critical first line of defense for dependable email delivery.

What is DMARC (and how does it relate to SPF & DKIM)?

Giving receivers instructions on how to manage emails failing authentication, DMARC is a DNS record acting in concert with SPF and DKIM. DMARC is a policy framework that states, "if an email from my domain fails the SPF/DKIM checks, here's what to do with it," whereas SPF and DKIM are authentication mechanisms. Using DMARC, domain owners can either tell recipients to reject or quarantine emails that fail tests or simply watch and report on them (no action). The aim is to reduce phishing and spam by greatly increasing the difficulty for unapproved senders to spoof your domain.

How DMARC Works: When an email comes in, the receiver first evaluates SPF and DKIM:

If at least one passes and is “aligned” (meaning the domain in the SPF/DKIM matches the sender’s domain), then the email is considered authenticated under DMARC.
If both SPF and DKIM fail (or pass but not aligned with the from-domain), DMARC policy kicks in. The DMARC record (published as _dmarc.yourdomain.com in DNS) will specify a policy: typically p=none (monitor only), p=quarantine (treat failing mail as suspicious, e.g. send to spam), or p=reject (outright refuse failing mail).

The domain alignment is crucial for DMARC to treat an email as entirely verified. This implies the domain used to sign the DKIM signature or the domain that passed the SPF check (the bounce/return-path domain) should match the domain in the "From" header of the email. One of the most frequent problems is misalignment; for instance, if an email passes SPF but still fails DMARC alignment because the return-path domain belongs to a third-party service rather than yours. In a later section on dangers, we will talk about how to approach that.

DKIM (DomainKeys Identified Mail): Although SPF and DMARC are our main concerns, DKIM is important to note as DMARC also depends on it. With a private key, your outbound mail server signs the headers of every email; receivers check it using your public key posted in DNS. DKIM employs two cryptographic keys. A valid signature confirms the email comes from a server approved by your domain and has not been altered in any way. Your DKIM signatures will have to match with your domain using DMARC; that is, the DKIM signing domain (d=) should be your domain or a subdomain of it. That way, a valid DKIM signature can still allow an email to pass DMARC even if it fails SPF (say, as a result of forwarding or other problems).

Why DMARC Matters for Deliverability: DMARC gives receiving servers assurance that emails from @yourdomain. com should be either correctly authenticated or disposed. This considerably protects your brand from phishing and spoofing. From a deliverability angle, properly verified emails (with SPF/DKIM passes matched to DMARC) are far less likely to be tagged as spam or refused by mailbox providers. On the other hand, if you have a strict DMARC policy and your messages aren't set up to pass it, you could inadvertently prevent your own rightful emails; hence testing and configuration are absolutely vital. Soon we will go through how to securely use DMARC.

Why SPF and DMARC Are Crucial for Reliable Email Delivery

Trust and Inbox Placement: SPF and DMARC tests are indicators used by email providers (like Gmail, Outlook, Yahoo, etc. ) to determine the veracity of an arriving communication. If your DNS is configured with SPF, DMARC (and DKIM), and everything passes, it informs the provider that the email is genuinely from your domain and has not been spoofed. Consequently, the communication is considerably more probable to arrive in the inbox. Providers could view your messages with suspicion if you lack these documents or they are improperly set. Actually, authentication results frequently determine whether a communication is delivered or discarded/marked as spam. According to industry statistics, businesses using SPF, DKIM, and DMARC experience much fewer malicious or fraudulent emails reaching consumers; properly authenticated emails often escape the spam folder.

Protection Against Spoofing: SPF and DMARC protect your domain's reputation beyond deliverability. DMARC with a quarantine/reject policy can outright block spoof emails claiming to be from you, while SPF guarantees only authorized servers may send as your domain. Without these, attackers could send phishing emails assuming to be your business (nothing in DNS specifies they can’t), and recipients' computers would have no automated means to identify those are false. Bad authentication configuration can therefore cause your domain to be employed in spam or phishing, hence harming your brand and maybe getting your domain banned. On the other hand, a robust SPF/DKIM/DMARC configuration aids in enhancing your sender reputation and maintaining smooth flow of legitimate emails to consumers while at the same time keeping hostile actors at bay.

Compliance and Requirement by Providers: As said before, the email ecosystem is heading toward widespread acceptance of these norms. Using your domain, several cloud email platforms and outside senders demand you to set up SPF/DKIM/DMARC. Some, such Google Workspace and Microsoft 365, strongly suggest it for all consumers to avoid delivery problems. Google and Yahoo have made having a correct DMARC policy a de-facto need for big-scale senders actually. Companies need to remember one thing: reliable email delivery requires SPF and DMARC now; it's not elective.

SPF & DMARC in Practice: Own Mail Servers vs. Third-Party Services

Not all business emails start in the same spot. Some through your company's own mail server (or web server), others through third-party channels (marketing tools, CRM systems, invoicing programs, and so on). Though there are a few differences: SPF and DMARC are just as crucial in the latter circumstances:

Sending from Your Own Server or Domain Email

Should your company operate its own mail server (or you utilize your web server to send emails from applications), you have to make sure your SPF record includes your server. This usually entails adding the server's IP address or hostname to the SPF TXT entry (e. g. , utilizing an ip4: mechanism or an include: if your mail is routed via a provider). Set up reverse DNS (PTR) for your mail server's IP if at all feasible; many receivers verify the IP has a PTR record matching your domain; lacking this might affect deliverability. Although it's not part of SPF/DKIM/DMARC, reverse DNS is a complementary DNS verification of your server.

DKIM is strongly advised for your own mail server: create a DKIM key pair and put the public key in DNS so outgoing emails get signed. This and a correct SPF entry for your domain's MX or sending IP will increase the likelihood that receivers trust your mail. At last, enforce these checks by posting a DMARC record for your domain. Start collecting reports on your mail streams with a monitoring policy (p=none; rua=mailto:you@yourdomain.com), then ratchet up to qarantine or reject once you're confident legitimate mail is passing authentication.

Using Third-Party Email Platforms (Mailchimp, CRMs, Invoicing Software, etc.)

Sending emails on your behalf using outside services is rather natural. Mailchimp could, for instance, be used to send a newsletter; Salesforce or HubSpot could be used to send CRM emails; an invoice app could be used to send consumer receipts. Usually necessary in these instances is additional SPF and DKIM setup so that these services may be permitted to send as your domain.

Most reputable third-party email platforms will provide instructions to “authenticate” your domain. Typically, this involves:

Adding an SPF include: e.g., if newsletterservice.com sends your emails, they may ask you to add include:newsletterservice.com (or their specific SPF subdomain) to your SPF record. This ensures their mail servers are considered valid senders for your domain. Failing to include a service’s mail servers in SPF can result in SPF failures for all those emails (since from the receiver’s perspective, the emails are coming from servers not on your list). For instance, if your accounting software sends via SendGrid or Amazon SES, you’d need to include those in SPF or use a provided include mechanism.
Enabling DKIM signing: Many platforms let you configure DKIM by providing you with a DNS record (often a CNAME or TXT) to publish. This allows them to sign emails with a DKIM key tied to your domain, which will pass DKIM checks. DKIM is especially important if SPF alignment can’t be achieved (more on alignment below). For example, Mailchimp no longer requires adding an SPF include for their servers – their emails may fail SPF alignment by design – but they rely on DKIM signatures to authenticate your domain instead. In such cases, setting up DKIM is crucial so that those emails still pass DMARC via DKIM (even if SPF fails).
Domain verification: Many services require verifying you own the domain (often via a link in an email or adding a TXT record) before they’ll send using your domain in the “From” address. This is a preliminary step to prevent abuse.

Pitfall – SPF Alignment and Return-Path: Under DMARC, one challenging component with third-party senders is SPF alignment. SPF checks use the domain of the envelope sender (sometimes called the return-path or bounce address). Your emails are often sent via their own bounce address (e.g. bounce@service.com), not your domain. This means that even if you include their servers in SPF and SPF passes, the domain that passed SPF is service. com, which does not match your domain in the “From” header hence DMARC's SPF alignment fails. Some companies thus omit SPF in favor of DKIM for DMARC aims. This is also why certain providers permit you to configure a custom return-path domain (like a subdomain of your domain) such SPF may match. If given that choice, it's wise to take it—that is, set up a custom bounce domain like bounces. yourdomain. com the service will use so that SPF checks match with your parent domain.

In short, always abide by their DNS configuration advice when employing third-party services. Publish their DKIM key records on your domain, double-check that these communications are passing DMARC alignment, and make sure you've included any required SPF include for their sending domains (unless they explicitly say not to). When you add a new service, it's simple to neglect this; a typical error is forgetting to change SPF/DKIM after beginning to deliver emails using a new tool, therefore causing abrupt deliverability issues.

Common SPF and DMARC Pitfalls (and How to Avoid Them)

Even with the right concepts in mind, there are some frequent misconfigurations that plague SPF, DKIM, and DMARC setups. Here are the most common pitfalls and how to address each:

Multiple SPF Records: DNS permits only one SPF record per domain. If you accidentally create a new TXT record for SPF while an old one exists (instead of merging them), both records become invalid. This can lead to SPF permanent errors or failed checks. Fix: Always maintain a single SPF entry. When you need to add a sender, edit the existing SPF string to include it, rather than adding a second record.
Exceeding DNS Lookup Limits: An SPF record can contain at most 10 DNS lookups (caused by includes, redirects, etc.). If you use many email services, all those includes can add up and break the 10-lookup rule, causing SPF to fail (receivers will see a “permerror”). Fix: Keep includes to only those truly needed. You can often omit redundant entries and/or use SPF “flattening” tools to convert includes into a list of IP addresses to cut down lookups. Regularly audit your SPF record for services you no longer use, and remove unnecessary includes.
Incomplete SPF Authorization: Forgetting to list a legitimate sending source in SPF is another common issue. The result is straightforward – emails from that source will fail SPF and likely be rejected or marked spam. Fix: Inventory all services that send email for your domain (including that no-reply address from your website, your CRM system, HR tools, etc.) and make sure every one of them is accounted for in your SPF. Update the record whenever you add or change providers.
SPF Syntax Errors: Something as small as a typo can break your SPF record. Missing spaces, incorrect mechanisms, or not wrapping the entire policy in quotes (depending on your DNS interface) can invalidate the record. Fix: Use an SPF record generator or checker tool to validate the syntax. And remember the correct format: start with v=spf1, list mechanisms (include/ip4/ip6/a/mx, etc.), and end with an ~all or -all.
DKIM Not Set or Misaligned: Some businesses skip DKIM setup, which leaves an authentication method on the table. Others enable DKIM but encounter DKIM alignment issues. Alignment means the domain in the DKIM signature (the d= value) should match your sending domain. If, for example, your email’s From is user@yourdomain.com but the DKIM signature is signed by thirdparty.com, then even if the signature is valid, it won’t count for DMARC alignment. Fix: Always publish the DKIM public key provided by your email platform in your domain’s DNS and ensure the service is signing emails as your domain. Many services let you specify the signing domain (often your own domain once verified). Test DKIM using tools or by sending to a mailbox at Gmail/Outlook and checking the email headers for DKIM-Signature to see the domain. Ensure the d= domain matches exactly (or is a subdomain under your domain if you use relaxed alignment).
Missing or Misconfigured DMARC: Not having a DMARC record means you’re missing out on the benefits of instructing receivers and getting feedback. But having a DMARC record with a bad setup is risky too. Common mistakes include setting a strict policy (p=reject) too soon without monitoring, or conversely leaving p=none forever (which doesn’t actively protect you). Another mistake is not using ruf/rua to receive reports, or ignoring the reports that are sent. Fix: Start with p=none and a valid email in rua to collect aggregate reports. Review the reports to identify any sources failing authentication (they can reveal misconfigurations or unauthorized use). Once you’re confident all legitimate mail sources are aligned and passing, move to p=quarantine or p=reject to enforce protection. Also consider subdomain policies (sp= tag) if you want to control or lock down subdomains separately. Remember to monitor on an ongoing basis – if you add a new sender and it shows up as failing in DMARC reports, take action before it impacts email delivery.
Domain Alignment Across Services: As discussed, a frequent pitfall is not addressing domain alignment when using third-party services. For example, using Mailchimp or AWS SES “out of the box” without setting up your domain will result in those emails failing DMARC (since they’ll appear to come from yourdomain.com but aren’t properly aligned). Similarly, having a mismatch between the Return-Path (bounce address) domain and your From domain can break SPF alignment. Fix: Whenever you use a new service, always configure the provided authentication settings (SPF include, DKIM, verified custom domain or return-path). If a service doesn’t support domain alignment, you may choose to send those particular emails from a distinct subdomain of your domain (with its own SPF/DKIM/DMARC) to isolate and manage alignment issues.

By being aware of these pitfalls, you can double-check your DNS records and sending practices to avoid the common errors that lead to deliverability headaches.

Consequences of Poor SPF/DMARC Configuration

It’s worth underscoring what can go wrong if SPF and DMARC are not properly set up, as the consequences can be serious for a business:

Emails Landing in Spam or Not Being Delivered: This is the most immediate impact. ISPs will often flag or refuse messages that fail SPF/DKIM/DMARC checks. If you’ve ever had customers say “I didn’t get your email” or noticed open rates plummet, an authentication failure could be the culprit. Without correct SPF/DKIM, your emails might get marked as spam or rejected outright, disrupting communication and marketing efforts.
Damage to Sender Reputation: Repeatedly failing authentication can harm your sending reputation. Mail providers use your domain’s history to decide if you’re a spammer; if many emails from you fail SPF or DMARC, it looks like you don’t control your sending or (worse) that spammers are spoofing you. This can make even future properly authenticated emails more suspect. Also, a misconfigured DMARC (like an unmonitored p=reject that is blocking legitimate mail) can inadvertently cause your domain to appear untrustworthy (due to bounces) unless quickly fixed.
Spoofing and Phishing Risks: If you don’t publish an SPF record or DMARC policy, it’s open season for attackers to forge emails from your domain. Your customers or partners could receive fake emails that appear to come from you (e.g., phishing emails attempting fraud). Such incidents can lead to financial loss and erode trust in your brand. A misconfigured SPF (like too lenient +all mechanism or expired include) similarly leaves gaps for spoofing. On the flip side, a strong SPF and DMARC setup significantly reduces successful impersonation attempts, with businesses reporting dramatically fewer phishing emails reaching their employees once these measures are in place.
Delivery Failures for Transactional Emails: Some of the most critical emails (password resets, invoices, system alerts) are often sent by automated systems or third-party tools. If those emails fail authentication, they might never reach the user, leading to poor user experience or even operational problems. For instance, an invoice that never arrives can delay payment, or a missed alert could disrupt service. Ensuring those systems are authenticated (via SPF/DKIM and passing DMARC) is crucial for reliability.
Troubleshooting Nightmares: Without DMARC reports, you may not even realize there’s a problem until a lot of emails have been lost. Then your team scrambles to figure out why emails are failing. Proactively having DMARC with reporting (and monitoring those reports) can save you from this reactive firefighting by highlighting issues early.

In short, poor SPF/DMARC configuration can lead to communication breakdowns, security incidents, and a damaged reputation. The good news is that these are preventable issues – with the right setup, you can maintain a strong sender reputation and high deliverability.

Actionable Recommendations for Reliable Email Deliverability

To ensure your emails reach the inbox and your domain stays protected, here are actionable steps and best practices:

Audit Your Email Senders: Make a list of all services and servers that send email using your domain. This includes your main mail server, web apps, marketing platforms, CRM systems, customer support tools, billing/invoicing software – everything. This inventory will drive your SPF includes and DKIM setup. It also helps you spot any sender that shouldn’t be there.
Create a Single, Comprehensive SPF Record: Consolidate all the sources from step 1 into one SPF TXT record for your domain. Use include: mechanisms for third-party services (as specified by their documentation) and/or IP addresses for your own mail servers. Ensure you don’t exceed 10 DNS lookups – if you’re near the limit, consider removing redundant includes or using a flattening tool to compress the record. Publish the SPF record and then test it (using online SPF checkers) to verify it’s valid. Remember to update this record whenever you add or remove a sender (stale DNS records can cause issues down the line).
Enable DKIM for All Email Sources: For each platform or server that can send as your domain, set up DKIM signing. This usually means generating a public/private key pair (or having the service provide one) and adding a DNS TXT record (often under selector._domainkey.yourdomain.com). Once in place, verify that emails from that source include a DKIM-Signature header and that it passes validation. DKIM adds a layer of protection and is particularly useful if emails get forwarded (which can break SPF) – as long as the DKIM stays intact, the email can still be authenticated downstream.
Publish a DMARC Record (Start with Monitoring): Add a _dmarc.yourdomain.com TXT record with at least v=DMARC1; p=none; rua=mailto:your-report@yourdomain.com. The p=none policy means no emails will be blocked; instead, you’ll receive aggregate reports about SPF/DKIM passes and fails. Use this phase to spot misconfigurations or unknown senders. It’s recommended to use a DMARC report analyzer tool or service to aggregate and visualize these reports for easier analysis. Over a few weeks, you should be able to identify if any legitimate emails are failing SPF/DKIM. Fix those issues as needed (e.g., update SPF includes, configure DKIM for that sender, etc.).
Move to Enforcement Gradually: Once your monitoring shows all legitimate mail is authenticating properly, change your DMARC policy to p=quarantine (perhaps with pct=50 to start, affecting 50% of mails) or straight to p=quarantine at 100%. This will direct failing mails to spam/junk. Monitor for any unexpected side effects. Finally, move to p=reject when confident – this instructs ISPs to drop emails that fail authentication entirely. By doing this gradually, you avoid accidentally blocking important emails while moving toward full protection. Always leave your report addresses (rua and optionally ruf) in place so you continue to get feedback even after enforcement.
Align Your Domains (If Using Third Parties): As part of the above, ensure that for each third-party service, you’ve achieved domain alignment. This may involve setting the service’s “From address” to use your domain (after domain verification) rather than a generic address. It might also involve configuring a custom return-path domain or subdomain they provide. Check DMARC reports or use tools to simulate an email from each service to verify that either SPF or DKIM (or both) pass with alignment. If a service cannot send with your domain in a DMARC-aligned way, consider using a subdomain for that service’s emails and adjust the DMARC policy for that subdomain separately (sp= tag can specify subdomain policy).
Use Testing Tools: Take advantage of free tools to test your email authentication. For example, services like Mail-tester, MX Toolbox, or specific SPF/DKIM/DMARC checkers will analyze an email you send them or inspect your DNS records. These can catch issues like DNS propagation problems, syntax errors, or missing includes. Some tools will also flag if your SPF is too long or if you’re nearing the lookup limit.
Monitor and Maintain: Setting and forgetting is dangerous in the email world. Designate someone or use a service to monitor DMARC reports continuously. This will alert you if, say, a new source starts sending unauthenticated email claiming to be your domain (could be a sign of compromise or a new third-party you forgot to configure). Also review your SPF/DKIM whenever you change email providers or add a new sending service – outdated records (like pointing to a deprecated service) can cause hard-to-track issues months later. Regularly rotating DKIM keys (where possible) is another security best practice.
Educate Your Team and Clients: Make sure your developers and IT staff understand at least the basics of SPF, DKIM, and DMARC. This helps ensure that when new projects or tools are adopted, email authentication is part of the setup checklist, not an afterthought. For clients (if you’re a development agency setting up things for them), explain why these DNS records are needed in non-technical terms – e.g. “This will prevent your invoice emails from going to spam and will protect your brand from email spoofers.” In our experience at Origami.Vision, taking a proactive stance on email authentication saves everyone headaches down the road.
Consider Subdomain Delegation for Third-Parties: If you use a lot of different third-party senders, managing everything under one root domain can get complex. One strategy is to give each major function a subdomain. For example, use news.yourdomain.com for newsletters via Mailchimp, billing.yourdomain.com for invoices via your billing software, etc. You can then publish SPF/DKIM/DMARC records on those subdomains specifically, without cluttering the primary domain’s SPF or risking one service’s issues affecting another. Receivers still see the emails as coming from your organization (just a subdomain variation), and you gain flexibility. Keep in mind, though, that DMARC’s default is to inherit top-level policy for subdomains unless you specify sp=, so if you use this approach, configure the sp tag or explicit records on the subdomain.

Following the above instructions will help you to establish strong email authentication posture. This means better security as you stop others from misusing your domain and better deliverability: your messages often land in inboxes. Properly configured SPF, DKIM, and DMARC collaborate to guarantee that you—and only you—control who can send emails under your domain and that mailbox providers trust those emails.

Conclusion

Email deliverability can make or break your communication with clients and users. As a development agency familiar with the pitfalls of transactional and marketing emails, we know that a little upfront work in DNS records saves a lot of trouble later. SPF and DMARC are indispensable tools in this regard – they verify your emails’ legitimacy and keep your domain’s reputation intact. Implementing them (along with DKIM) might require a bit of technical effort, but the payoff is clear: fewer emails in spam, fewer lost messages, and a stronger defense against spoofing. In summary, investing time in SPF and DMARC configuration is investing in your business’s reliability and credibility in every inbox. With the actionable tips provided, both developers and business owners can ensure their email infrastructure is solid. Here’s to safer and more successful emailing, backed by the right DNS records and policies!