Email authentication is a method for confirming that you, as a sender, are really who you claim you are, which makes it more difficult for hackers, spoofers, spammers, and other cybercriminals to impersonate you. Since Simple Mail Transfer Protocol (SMTP) does not have its own built-in authentication protocols to prevent impersonation, it is important to implement these measures separately. 

Based on authentication results (i.e., success or failure), the receiving server can understand whether it’s safe to deliver a given message to the inbox or if it should instead be sent to the spam folder or be discarded entirely. If you do not authenticate your emails or do it incorrectly, they might be marked as spam or get rejected. It is important to set up not just a single authentication method but multiple ones and always ensure they are monitored and devoid of mistakes. Well-implemented and maintained email authentication protocols (SPF, DKIM, and DMARC) can help you prevent failed authentication checks and issues with email deliverability. 

In this article, we will explore the five most common email authentication mistakes businesses make and provide recommendations on how to avoid them. 

1. Misconfigured SPF Records

Below is a list of common SPF record misconfigurations, along with a concise description of their potential impact and actionable steps to fix such misconfigurations. 

Common Mistakes

• More than One SPF Record: Each domain should have only one SPF record. When you have more than one SPF record, you might experience validation failures. For example, this might cause a SPF permanent error, email non-delivery, and SPF authentication failure. In the worst case scenario, this might lead to loss of reputation, spam, and successful phishing attacks.
• Exceeding the DNS Lookup Limit: SPF records are limited to 10 DNS lookups. When you surpass this limit, you might encounter authentication errors.
• Incomplete Authorization: If you fail to include all legitimate mail servers in the SPF record, this might result in email rejections.

Impact 

Misconfigured SPF records can cause emails to fail authentication checks. This, in turn, will negatively impact deliverability and expose your domain to spoofing attacks.

How to Fix Misconfigured SPF Records 

• To avoid having too many SPF records, you can consolidate multiple SPF records into one single record by using the include mechanism.
• You can optimize your SPF record to stay within the 10 DNS lookup limit by removing repetitive, redundant entries or flattening the SPF record.
• You should regularly update your SPF record to reflect changes in your sending infrastructure.

2. DKIM Failures Because of Incorrect Setup

Here are some of the most common DKIM failures due to incorrect setup. 

Common Mistakes

• Public Key Not Mentioned: If the DKIM public key isn’t published in DNS, then you will experience authentication failure. 
• Syntax-Related Errors: Poor formatting or missing characters in DKIM records can potentially invalidate them.
• DKIM Alignment Issues: The d= value within the DKIM signature must match the domain found in the “From” address. If these two do not match, check failures are very likely. 

Impact

DKIM failures compromise email integrity, which makes it easier for attackers to alter messages during transit.

How to Fix DKIM-Related Failures 

• Use a DKIM record generator to help avoid syntax errors.
• Publish the public key in your domain’s DNS settings.
• Ensure proper alignment between the d= value and the “From” address domain.

3. A DMARC Policy that Is Either Too Strict or Too Lenient 

Choosing the correct DMARC policy is often a challenge for modern businesses.

Common Mistakes

• Strict Policies Without Monitoring: Setting DMARC policies (e.g., p=reject) without monitoring them properly and regularly can block legitimate emails.
• Lenient Policies (p=none): A “none” policy offers only minimal protection, which makes the domain more vulnerable to spoofing and phishing attacks.
• Ignoring Subdomains: Applying DMARC only at the top-level domain can leave lower-level domains (i.e,. subdomains) vulnerable to different kinds of cyber attacks. 

Impact

When your DMARC policy is too strict or too lenient, this can either block even safe, legitimate emails or fail to protect against malicious activity. Both of these scenarios may be detrimental to a business’s reputation. 

How to Fix DMARC Policy Issues  

• You should first start with a p=none policy and continuously monitor activity using DMARC reports.
• Then, gradually move to stricter policies (p=quarantine or p=reject) once you are ready and comfortable to do so. 
• You should also configure separate policies for subdomains if necessary.

4. Not Conducting Regular Updates and Monitoring

Not monitoring records actively or failing to conduct regular updates is also a big mistake that businesses make today. 

Common Mistakes

• Outdated DNS Records: When you do not update your DNS records when switching email providers or adding new servers, you might often experience authentication checks.
• Not Paying Attention to Authentication Reports: Businesses often do not pay adequate attention to DMARC aggregate reports, as a result of which they miss out on important insights into their email ecosystem.

Impact

Outdated configurations reduce deliverability rates and make domains vulnerable to spoofing attacks.

How to Fix Update and Monitoring-Related Issues

• Always audit your DNS records to make sure they are complete and accurate. 
• Use DMARC analyzers, which can help you easily analyze DMARC reports and thereby identify issues faster.
• Make use of automated monitoring systems for continuous oversight of your email authentication setup.

5. Misaligned Domain Settings Across Different Platforms

Oftentimes, businesses fail to align domain settings across various platforms. 

Common Mistakes

• Using Third-Party Services Without Proper Authentication: Many businesses fail to align their domains when using third-party services like Mailchimp or AWS SES. This may result in SPF or DKIM failures.
• Return-path Mismatch: The “Return-path” domain often doesn’t match the “From” address domain, which breaks the SPF alignment and results in deliverability failures.

Impact

Misaligned settings lead to authentication failures and poor sender reputation.

How to Fix It

• You should configure custom Return-path domains that match your “From” address domain exactly. 
• Always authenticate third-party services with proper SPF and DKIM setup.
• Test domain alignment with the available online tools before sending bulk emails.

Why Is Email Authentication Important

Email authentication protocols significantly improve deliverability rates by ensuring emails are trusted by ISPs. For example:

• Organizations that implement SPF, DKIM, and DMARC report 62% fewer Business Email Compromise attempts reach their employees’ inboxes.
• In 2024, 53.8% of senders said they were using DMARC, which is much higher compared to the 42.6% in 2023. This is a clear sign of increasing adoption because of the protocol’s effectiveness in preventing spoofing attacks.
• Correctly authenticated emails are less likely to be flagged as spam or be rejected by mailbox providers entirely.
• Authentication helps reinforce brand reliability and improves customer trust by protecting against phishing attempts.

Actionable Tips for A Better Email Authentication Experience

Here are several additional tips for optimizing your email authentication setup:

1. Try Using Only Verified Tools: Employ reputable tools for testing SPF/DKIM/DMARC configurations. To understand which tool is best for your needs (e.g., a DMARC checker tool), you should carefully analyze their offering while also reading user reviews to ensure the tool has been successfully tested and liked by users. 

2. Educate Your Team: Regularly train your IT teams to help them understand how these protocols work together and thereby empower them to stay protected against ever-evolving cybersecurity threats. 

3. Monitor Reports: Analyze DMARC aggregate reports on a regular basis to gain insights into failed checks and act accordingly. 

4. Rotate Keys: Periodically rotate DKIM keys to boost your security.

5. Make Use of Automation Services: There are numerous tools in the market for automated monitoring and troubleshooting that you can use to reduce the likelihood of manual error or oversight. 

Final Words

Email authentication may lead to serious problems for businesses, including failed marketing efforts, loss of profits, reputational damage, and endangered sensitive information. In this article, we covered some of the most common email authentication mistakes that businesses make, such as SPF record misconfigurations, incorrect setup-related DKIM failures, overly strict or lenient DMARC policies, lack of monitoring and regular updates, and domain settings mismatch across different platforms. 

We also provided key insights on what impact these mistakes can have on your business and what steps you can take to avoid such mistakes. Acting proactively and fixing these errors can help you significantly boost your email deliverability rates, reduce spam, and enjoy financial and reputational gains.