What Is SpamAssassin?

email deliverability checklist cover
In the world of cold emailing or email marketing, one thing we all want to avoid is being tagged as spam.

If at any point your email is tagged as spam, it has repercussions for all of your future efforts. Repercussions that it takes some time to come back from.

In this blog, we’ll help you understand spam filtering systems better, and provide you with email best practices to lower your spam score.

What Is SpamAssassin?

spam assassin infographic
SpamAssassin is one of the most popular email filtering systems out there as it is open source.
It helps users by blocking, marking, and filtering out emails that they find untrustworthy and may be spam or malware.

Among the filtering techniques SpamAssassin uses to determine spam are:

  • DNS blocklists such as SORBS or Barracuda
  • Text analysis for your email header and body copy
  • Bayesian filtering
  • Collaborative filtering databases, such as email firewalls

The filter will produce a score based on how the email performs against these checks. This score determines whether your email makes it through to your recipient.

Due to the exhaustive nature of the tests, it is difficult for spammers to make it through.

Legitimate emails will make it through all of the above and successfully arrive to recipients.
For email marketers or salespeople, however, this may be more of a gamble.

After all, you’re emailing multiple people daily to offer them your solution. You should have done your research and been targeting the right people with the right messaging, but it is possible to still fall through the cracks or for someone to mark you as spam.

To take the correct steps if you are marked as spam, you should monitor your SpamAssassin score, given its popularity as a spam filter.

SpamAssassin Score

The SpamAssassin score is related to the likelihood of an email being spam. The higher you score, the higher the chances are that the filter will consider you to be spam.

How does it work?

For each of the tests mentioned above that SpamAssassin runs, your email receives a numerical score. Positive numbers are for possible spam, while negative numbers mean it is unlikely.

The final number you get is the total of all the scores added up. If this total is higher than the threshold set by the software administrator, then the email will be marked as spam.

The default threshold score is 5, with 10 being considered the highest. This should not be considered the rule, however, as system administrators can adjust that to be higher or lower.

Aiming for a score of 0 or closer to 0 is best:
spam assassin test infographic
Tools such as GlockApps will help you determine how your email copy and settings will be received by the SpamAssassin filters. Based on this, you can take the appropriate steps to fix it before sending out your campaigns.

But this is not the only thing you can do to lower your spam score.

Best Practices to Lower Spam Score

There are some best practices you can follow to succeed at connecting with your prospect’s inboxes despite the SpamAssassin filters:
spamassassin best practices infographic

Avoid the use of spam words, strange text formats, hyperlinks, attachments, or images

Spam checkers exist for a reason, so making use of them to ensure that your email copy doesn’t have any spam words makes sense. Especially when spam words increase every day.

Additionally, make sure to avoid strange text formats, such as bolded, italicized, or words in all caps. All of these are indicators and features of spam email and will not make it through filters. Even if they are in your email signature.

A good rule of thumb is to have a separate email address or domain exclusively for email outreach. You should keep your signature clean and simple to increase your chances of landing in a prospect’s inbox.

This also helps you avoid hyperlinks in your signature for campaigns, as hyperlinks of any kind are also a feature of spam emails, and therefore likely to be marked as such. Images in signatures or anywhere else in the email will also land you in spam, as will the use of attachments.

Remember, the purpose of email outreach is to begin relationship building. It is not to immediately get into the nitty-gritty of how you can help your prospects.

Providing them with white papers or graphs at this point in time is detrimental not only to their reaction to your outreach but also to your email deliverability.

Set up email authentication

Email authentication is an extremely important, technical step that has been historically overlooked.

With the arrival of more and more spam filters and spammers, however, it is not something that can be ignored if any part of your work is conducted via email.

Setting up SPF, DKIM, and DMARC does indeed take time, but your efforts will be well worth it when your email arrives in your prospect’s inbox and is not marked as spam.

IT folks are generally not familiar with the intricacies of these authentication tools, and indeed it is salespeople and marketers who benefit the most from them.

Email authentication setup signifies to other ISPs that you care enough about avoiding spoofing and spammers that you took the time to protect yourself. This is why SpamAssassin actively checks for the application of at least one of these methods, though the use of all is best.
Not sure if you’ve got your DNS settings arranged properly?

We’ve created a free DKIM/SPF Checker so that you can be sure your email is authenticated before starting your campaigns. GlockApps and similar tools will also inform you about this.

And most recently, Gmail has added DKIM to its basic email settings.

Test your email deliverability before sending

Basic rule for sending out mass emails?

Do not send them before knowing where your emails might end up.

Where they end up will affect your email address and domain’s reputation, and any future campaigns you send out will have to paddle upstream to reach your prospect’s inboxes.

We mentioned GlockApps above as a tool that can help you figure out where your emails are landing. This is something you should do for your email addresses and domains on a weekly basis when you are sending large campaigns or multiple emails per day.

It is best to know where you will end up before ending up in spam and losing out on connecting with these prospects. After all, if this happens, not only do you have to dig yourself out of spam, but you will not be able to target certain prospects for a while.

Knowing this before you send out the email gives you time to strategize and fix it, and then attempt to connect with prospects.

Warm up your email to have a high engagement rate

Engagement rates are a tell-tale sign of an email used for purposes that are not spam.

As salespeople utilizing email, though, this can be difficult to achieve, especially when you are first starting out with a new address or domain, or revitalizing an existing email.

Warm is a warm up tool that helps you have a high engagement rate from the get-go.

By artificially creating email threads and conversations, your email’s engagement rate is healthy and will be seen favorably by filtering systems such as SpamAssassin.

With additional manual seeding, you will keep your spam score nice and low.

And by providing proper value, your engagement rate will slowly increase naturally.

Keep your lead lists clean and validated

And finally, remember, you are not a spammer.

Yes, you are targeting and messaging multiple prospects, but if you’re a good SDR with a clear Ideal Customer Profile, your messaging should be on point.

That means providing value to your prospects by following cold email best practices:

  • Do your research and target the correct audience
  • Understand the industry and how your product or service fits as a solution
  • Concisely present this via email
  • Stand out by demonstrating your knowledge of your prospect and how your product or service may serve them
  • Utilize humor appropriately to stand out
  • Keep it short, sweet, and to the point
  • Finish off with a clear call to action

All of this provides value to your prospect.

Either by providing brand awareness of your company or by informing them that there may be a solution for a problem they have that they can look into now or in the future.

Providing value to the right prospects means they won’t label you as spam, because you are not. You are offering them a solution.


Spam filters are here to stay, of that, there is no question.

And with the passage of time, they become even more stringent in their checks.

Salespeople and email marketers likewise still need to metaphorically knock on doors via email.

Ensuring that your email does not end up in spam is an ongoing task for all salespeople, but one that can be achieved with the right tools.

Join our launch list at Warm to know when it will be ready and for more information on making sure your email always makes it into your prospect’s inbox!
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