Email filtering has come a long way. We've gone from basic keyword matching to sophisticated AI-powered systems able to discern the most subtle nuances of spam.
Leading this evolution is SpamAssassin, a renowned email filtering software that evaluates how “spammy” your emails appear based on things like wording, formatting, and technical setup.
For email marketers, keeping your SpamAssassin score optimal presents both a challenge and an opportunity. The system may seem cryptic at first glance, but it actually follows clear, logical patterns you can learn to master.
And when you understand how the algorithm works, you go from a marketer who hopes their emails reach the inbox to one who knows they will. So, how exactly do you check your score, and more importantly, how can you keep it optimal? Let's find out.
What is SpamAssassin Score?
SpamAssassin is an open-source email filtering system developed by the Apache Software Foundation in 2001. Its primary job is to determine whether an email should be marked as spam based on a detailed scoring system.
To assign email scores, the software analyzes everything from your sending infrastructure and authentication records to your content patterns and HTML formatting.
Each of these elements can either add or subtract points from your total score. Interestingly, a lower SpamAssassin score indicates legitimate emails, while a higher score suggests potential spam.
What makes SpamAssassin particularly powerful is its ability to adapt and learn. It uses a combination of pattern matching, machine learning, and real-time blacklist checks to make intelligent decisions about email legitimacy.
Why does any of this even matter? As of December 2023, spam messages accounted for over 46.8% of the total email traffic generated for that month alone. And that’s one of the lowest records of spam we've seen in years.
SpamAssassin is among the most effective tools used by email clients, system admins, and even email senders to fight the spam epidemic and determine email deliverability.
How Does the SpamAssassin Scoring System Work?
SpamAssassin uses a point-based system to assess the chances of an email being spam. Each email is analyzed across various factors, and points are either added or subtracted based on how "spammy" certain elements appear.
The default spam threshold is 5.0 with the maximum value set at 10. Emails scoring below 5.0 are likely to end up inboxes, while those above face a higher risk of landing in spam. The best scores actually dip into negative numbers.
While 5.0 is the base value, email providers and system admins can adjust this number based on their preferences. Some conservative systems might reject emails scoring above 4.0, while others show more flexibility.
This variation means it’s important to aim for the lowest possible score rather than simply trying to skate under the default threshold.
Key Factors that Influence Your SpamAssassin Score
As mentioned, SpamAssassin looks at a variety of elements to determine whether your email is trustworthy or likely to be spam. Consider these factors to give your messages the best shot at landing in inboxes:
Email Headers and Body Content
SpamAssassin thoroughly inspects both your email headers and content, looking for suspicious signals and inconsistencies.
Your email header contains system information that’s typically hidden from view by default but still accessible if you’re keen to. We'll look a bit more closely at the circumstances surrounding email headers below.
As for your email content, the system checks for quite a number of signals, including:
- Excessive punctuation and shady formatting
- Overly large font sizes and flashy colors
- Sloppy HTML email code
- Unbalanced image-to-text ratios
- Hard-sell phrases and spam trigger words
- Broken or excessive number of links
- Poor grammar
Even when used innocently, certain phrases (e.g., “buy now,” “free,” etc.) can add points to your score if they resemble spammy patterns, so it’s important to balance your marketing messages with professional restraint.
Email Subject Lines
Your email subject line sets the first impression. For example, with your email content, SpamAssassin checks for excessive punctuation, ALL CAPS, and spam trigger words (like "EXCLUSIVE DEALS" or "Act Now!!!") when determining scores.
To avoid raising your score, keep your subject lines clean and relevant to your topic. Also, steer clear of marketing hype that might trigger red flags.
Technical Setup
SpamAssassin also considers technical configurations like your authentication and DNS records when assigning a score. If your email is missing any of the records, you’re almost guaranteed to lose points and your messages could end up in spam:
- Mail Exchange (MX) record
- Sender Policy Framework (SPF)
- DomainKeys Identified Mail (DKIM)
- Domain-based Message Authentication, Reporting & Conformance (DMARC)
These protocols verify your identity as a legitimate sender, so skipping them could have your emails flagged.
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Sender Reputation
How you manage your email list directly affects your sender reputation, which, in turn, influences your SpamAssassin score.
High bounce rates, spam complaints, and irregular sending patterns all contribute to a poor sender reputation, and by extension, a higher SpamAssassin score.
The solution? Never buy contacts, regularly scrub invalid accounts from your list, keep a consistent sending schedule, use double opt-in, and allow for easy unsubscribes to protect your sender reputation.
DNS Blocklists Checks & Bayesian Filtering
Your sending habits and engagement rates typically determine whether or not your email is added to blocklists. And once your sending IP or domain is on a DNS blocklist, your SpamAssassin score automatically increases.
SpamAssassin also uses Bayesian filtering to learn from previous spam patterns and adjusts its evaluation as new data becomes available.
How to Check Your SpamAssassin Score
Here's a simplified breakdown of two common methods to access and check your SpamAssassin score:
Inspecting Email Headers
This method requires a bit of technical know-how. Every email contains a hidden layer of information in the email header.
During email deliverability tests, these headers reveal details about the sender, recipient, and technical aspects of the email. And within these headers lie clues about your SpamAssassin score.
Here are the two most important headers to look for:
- X-Spam-Status: This header indicates whether your email has been flagged as spam by SpamAssassin along with a breakdown of the tests performed and the score required to pass. "YES" means it's been flagged, while "NO" indicates a clean bill of health.
- X-Spam-Level: Your X-Spam-Level visually displays your SpamAssassin score by showing an approximate amount of asterisks for each point (rounded to the nearest whole number). For example, a score of 3.2 would show as ***. If your score is 0 or a negative value, this header field returns empty.
While header analysis works, it's not exactly user-friendly. That's why many email marketers turn to specialized tools that make the process much simpler.
Leveraging Email Verification Tools
Email verification tools like Instantly.ai can help streamline the process of checking your SpamAssassin score and interpreting the results to drive better outcomes.
In practice, Instantly’s email verification feature:
- Runs advanced email validation check on your emails
- Provides detailed scoring breakdowns and reports
- Offers tailored improvement suggestions
- Tracks your scores and metrics over time to better inform your decisions
In short, Instantly handles the technical heavy lifting, leaving you to focus on running exceptional campaigns. Try it for free today!
9 Proven Tips to Improve Your SpamAssassin Score
Finding success with SpamAssassin isn't as complicated or demanding as it seems. The software guidelines clearly state that legitimate senders don't have anything to worry about.
Plus, even if they miss the mark sometimes, the software is (mostly) discerning enough to judge their overall practices correctly.
That being said, marketers shouldn't leave things to chance. Keep these tips top-of-mind to keep your SpamAssassin score low and your deliverability high:
Authentication and Technical Configurations
Strong technical foundations dramatically improve your score. To start on a proper footing, ensure your MX, SPF, DKIM, and DMARC records are correctly implemented.
When properly configured, these protocols show SpamAssassin that your emails are not forged or spoofed, which plays a significant role in improving your score.
Verify Your Domain & Emails
Another important element to consider for lower SpamAssassin scores is verifiable emails and domains. Specifically, your "from" and "reply-to" email addresses need to use domains that are easy to look up and verify.
Having a valid, authenticated domain makes your emails appear legitimate, which SpamAssassin takes into account when scoring.
Write in a Natural, Professional Tone
The way you write your emails significantly impacts your score. It sounds obvious but it’s important to write naturally—like you're talking to a real person (because you are).
Practically speaking, this means avoiding odd capitalizations, excessive punctuation, and gimmicky formatting like "F.R.E.E" or "ACT NOW!!!" These practices scream spam to every email filtering software around, including SpamAssassin.
Use HTML Cautiously
If you use HTML, make sure it's clean and validated. Poor HTML formatting is often associated with spam, especially when generated from word processors like Microsoft Word.
To avoid this, run your HTML through a validator to catch issues like unbalanced tags and missing attributes. And always include a text version for recipients who prefer it—this small detail can go a long way in reducing your spam score.
Avoid Image-Only Emails
Sending emails with just images is another red flag. SpamAssassin sees image-only emails as a tactic spammers use to bypass filters.
To avoid being penalized, always balance your images with a healthy dose of text and add relevant alt text to describe the images.
When in doubt, include more written content. Not only does this help with accessibility but it also shows SpamAssassin (and other spam filters) that your email has valuable information.
Use Professional Email Tools
The tools you use to send emails also play a major role. Professional email marketing platforms (like Instantly.ai) help ensure your messages follow best practices, like including proper MIME sections, valid message IDs, and correctly formatted headers.
On the other hand, bulk email tools that promote “stealth sending” are often used by spammers, and association with such tools can flag your emails to spam filters like SpamAssassin.
Avoid Spam Triggers & Suspicious Links
Referencing trigger words in high-impact industries like weight loss, gambling, and medications can also raise your spam score. If your business operates in these industries, it's especially important to keep your messaging clear and focused.
Similarly, links that lead to domains with poor reputations are a common spam trigger. Before linking to external websites, verify their reputation and whether they’re on any blocklists.
Even legitimate businesses can have bad reputations, and linking to them may hurt your SpamAssassin score. In short, links to reputable and verified sources only.
Don’t Force Reader Actions
Never ask recipients to open your email in a different tool or browser just to view your content correctly. This tactic is another common tactic used by spammers, so it's almost guaranteed to raise your SpamAssassin score.
Instead, put in the work to ensure your email design displays correctly across different devices and email clients before sending them.
Stay Compliant with Anti-Spam Laws
Last but certainly not least, always stay compliant with relevant privacy and anti-spam laws like the GDPR and CAN-SPAM.
In practice, this involves using double opt-in to ensure recipients are genuinely interested and providing obvious unsubscribe buttons within every email you send. Basically, avoid any tactics that could appear shady or misleading.
Compliance also ensures your emails don’t end up on blocklists—something SpamAssassin actively checks for when calculating your score.
Key Takeaways
As one of the leading email filtering software today, SpamAssassin holds a lot of sway in deciding whether emails reach inboxes or spam folders. And by staying mindful of its rules, improving your email deliverability becomes much less difficult.
Short on time? Here’s a quick rundown of the highlights:
- For marketers, SpamAssassin isn't the enemy, but a valuable indicator of your email deliverability health and a solid ally in the fight against spam.
- Improving your SpamAssassin score boils down to building a solid technical foundation, keeping content quality high, and continuously checking your practices against relevant laws and industry guidelines.
- If you’re looking to avoid manually tracking scores and troubleshooting issues, you'll want to engage with a reliable email optimization platform like Instantly.ai.
Thanks to Instantly's advanced optimization features and hands-on approach, you can effortlessly achieve better deliverability to improve your campaigns. You focus on strategy, we handle the technicalities. Sign up for free today.
