How do email senders get on Spamassassin whitelists and is there an application process?
Matthew Whittaker
Co-founder & CTO, Suped
Published 1 Aug 2025
Updated 16 Aug 2025
6 min read
SpamAssassin is a widely used open-source spam filtering system that helps identify and block unwanted emails. It functions by analyzing incoming messages for various characteristics and assigning a score based on how likely an email is to be spam. A higher score typically means the email is more likely to be spam and might be quarantined or rejected. Conversely, a negative score indicates a higher likelihood that the email is legitimate (often called "ham"), helping it bypass filters.
Within SpamAssassin, there are mechanisms to whitelist specific senders or domains, effectively giving their emails a better chance of reaching the inbox. This is distinct from general email blocklists (or blacklists) that identify known spam sources. Many senders hope to get their domains onto a global SpamAssassin whitelist to ensure their emails are delivered. This raises the question of whether there's an application process or a specific path to achieve this privileged status.
Understanding how SpamAssassin works
SpamAssassin utilizes a vast array of rules to evaluate incoming mail. Each rule, when triggered, adds or subtracts points from an email's overall score. For instance, an email failing a common spam check might gain a positive score, pushing it closer to being marked as spam. Conversely, passing certain authentication checks can lead to negative scores, pulling it away from the spam folder.
Users or administrators can implement their own whitelist rules. These are typically added in configuration files such as local.cf or sauser.cf, where specific email addresses or domains can be designated as trusted senders. This is a common way for an individual user or server administrator to ensure they receive mail from known contacts.
Example of whitelisting in SpamAssassin's local.cfconf
The rules whitelist_from and whitelist_from_dkim are key for this, as detailed in the SpamAssassin configuration documentation. However, these local whitelists are different from the global whitelists that are part of the SpamAssassin project's core ruleset.
The internal SpamAssassin whitelists
The specific rules that often spark curiosity are USER_IN_DEF_DKIM_WL and USER_IN_DEF_SPF_WL. These rules are known to assign a very significant negative score, typically around -7.5, which can dramatically lower an email's overall spam score and ensure it reaches the inbox. It has been observed that a much larger number of senders trigger these rules than the small handful of domains hardcoded directly into the 60_whitelist_dkim.cf and 60_whitelist_spf.cf files.
The explanation for this discrepancy lies in another rule file: 60_whitelist_auth.cf. This file contains a more extensive list of domains that are whitelisted based on their authentication status (SPF or DKIM). It's where you'll find domains from various companies, not just the tech giants. This indicates that while some domains are specifically whitelisted for SPF or DKIM, a broader set benefits from these authentication-based whitelists.
Understanding SpamAssassin
SpamAssassin is a robust, open-source email filter that assigns a score to each email based on hundreds of tests. This score determines whether an email is legitimate or spam. While it's highly configurable, its default ruleset is what many smaller email providers and corporate mail servers utilize. Even if major mailbox providers use their own proprietary filtering systems, understanding SpamAssassin's mechanisms can provide valuable insights into general anti-spam logic.
Is there an application process? The reality of SpamAssassin whitelists
A common misconception is that there's a formal application process to get onto SpamAssassin's global whitelists. The reality, as confirmed by a committer to the SpamAssassin project, is that there is no proactive process for senders to apply. Entries are added very rarely and typically only when a project committer observes a consistent need, such as frequent false positives or borderline scoring for legitimate, highly valued emails from a sender known not to send any spam.
The addition or removal of entries is generally ad hoc and unilateral, driven by actual problems experienced by SpamAssassin users. This means the default state for most senders is not to have an entry on these lists. The project's bias is towards stability, not agility in adding or removing domains, making it highly unlikely for new entries unless there's a compelling, widespread issue that needs addressing.
Limited scope
Even if your domain were on a SpamAssassin whitelist, its impact would be limited. Major mailbox providers like Google and Yahoo do not rely on the default SpamAssassin rule set. They employ their own sophisticated, proprietary filtering systems. While some commercial filters might have been built on the SpamAssassin engine in the past, many have evolved to use their own refined rule sets, rendering the default SpamAssassin lists less relevant for high-volume sending.
SpamAssassin whitelisting
There is no formal application process for inclusion on the global SpamAssassin (or blocklist) whitelists. Entries are hardcoded by project committers. Inclusion is rare and happens only when significant, recurring false positives are observed for high-value email from known non-spammers. The focus is on fixing specific problems for users, not on proactive sender requests.
General deliverability best practices
Improving your email deliverability universally requires focusing on core principles. This includes ensuring proper email authentication (SPF, DKIM, DMARC), maintaining a clean sender reputation, sending relevant content to engaged recipients, and avoiding spam trap hits. These efforts yield far greater returns than pursuing specific SpamAssassin whitelists.
What senders can do to improve deliverability without direct whitelisting
Since direct whitelisting on SpamAssassin's core lists is not a viable strategy for most senders, focusing on universal email deliverability best practices is paramount. The cornerstones of good deliverability include properly configuring your email authentication protocols like SPF, DKIM, and DMARC. These protocols prove that your emails genuinely originate from your domain and haven't been tampered with.
Beyond authentication, maintaining a positive sender reputation is critical. This involves consistently sending wanted, engaging content to a clean, opted-in list, and promptly removing inactive subscribers. Monitoring your deliverability through tools like blocklist monitoring and analyzing engagement metrics (opens, clicks, complaints) will give you actionable insights into your performance.
Views from the trenches
Best practices
Actively maintain your sender reputation through consistent authentication and positive recipient engagement.
Common pitfalls
Assuming that being on a SpamAssassin whitelist is a primary driver of deliverability for major mailbox providers, which is often not the case.
Expert tips
Focus your efforts on broad deliverability strategies like list hygiene and content quality, as these impact all recipient systems.
Expert view
Expert from Email Geeks says that the SpamAssassin default rule set isn't used by most major mailbox providers or filtering companies, and even filters built on its framework typically use their own rulesets.
2021-06-28 - Email Geeks
Expert view
Expert from Email Geeks says that SpamAssassin likely includes a list of known domains as a basic configuration or example, allowing administrators to add more domains as needed rather than it being a definitive whitelist to get into.
2021-06-28 - Email Geeks
Key takeaways
While the allure of being on a global SpamAssassin whitelist is understandable, the reality is that there's no official application process for senders. The inclusion of domains on these specific lists is a rare, internal decision made by the project's committers to address particular false positive issues for highly valued, legitimate email streams.
For the vast majority of email senders, efforts are far better spent on implementing robust email authentication, maintaining a healthy sender reputation, and ensuring consistent engagement with recipients. These foundational practices are universally recognized and will have a much more significant impact on your email deliverability success across all inbox providers, regardless of their specific spam filtering technologies.
Google and 
Yahoo do not rely on the default SpamAssassin rule set. They employ their own sophisticated, proprietary filtering systems. While some commercial filters might have been built on the SpamAssassin engine in the past, many have evolved to use their own refined rule sets, rendering the default SpamAssassin lists less relevant for high-volume sending.
