According to Statista, nearly 45.6 percent of all emails worldwide were identified as spam in 2023. This very high percentage of spam emails is a cause of alarm and concerns recipients and email marketers alike.
Spam emails can pose security risks, as they may contain malicious links or attachments designed to compromise personal information or devices. They are also annoying because they clutter inboxes, making it difficult for users to find genuine and important communications.
But how can you get rid of spam? Well, you can check each and every email that you get every day and delete the ones that you don’t need. But that’s nearly impossible and highly inconvenient.
So, what’s another solution to this? The answer to this lies in spam filters. In this guide, we will discuss what spam filters are, why they're important, how they work, and how you can safeguard your emails against them.
What is a spam filter?
A spam filter is a tool or software designed to identify and block unsolicited, suspicious, and potentially harmful emails sent in bulk.
Although much spam is relatively harmless, email providers use spam filtering to ensure their users have a smooth and hassle-free experience, as they can be disruptive to the overall email experience and also lead to more serious security issues.
Why do spam filters exist?
Today, all major email clients use spam filters to protect their recipients. Let’s take a look at the reasons why spam filters are so crucial.
Spam filters help block potentially harmful emails that may contain malware, viruses, or phishing attempts, thus protecting users' devices and data.⠀
Spam filters safeguard you against a Denial-of-Service (DoS) attack. A Denial-of-Service (DoS) attack aims to make a machine or network unavailable to its legitimate users by overwhelming it with excessive traffic. Spam filters block these emails, thus preventing resource overload and reducing the risk of network disruptions. This ensures that the users have smooth access to resources.
Spam filters help keep email inboxes clean by filtering out irrelevant or unwanted messages, making it easier for users to focus on the important ones.
How do spam filters work?
Typically, email providers use a combination of various filtering technologies that create a strong barrier between the recipients and spam. Two major techniques are used to filter out spam emails. Let’s take a look at them:
Heuristic analysis and user feedback
Heuristic analysis involves examining emails for specific characteristics often associated with spam, such as certain phrases, dubious sender information, unusual attachments, or irregular patterns. Emails with these traits are flagged as spam.
In addition to heuristic analysis, user feedback plays a crucial role. When users receive spam emails, they may mark them as spam. This manual tagging allows the filter to adapt to individual user preferences and better handle future emails from the same sender.
Bayesian filtering and machine learning techniques
This approach involves comparing the content of incoming emails with previously classified spam based on user feedback. It employs a specialized form of machine learning that uses statistical techniques. These algorithms examine large datasets to uncover complex patterns, predict future behaviors, recognize new spamming tactics, understand subtle differences in email content, and enhance the filter's criteria for better accuracy and protection against phishing and other threats.
Each email is assigned a spam score based on the aforementioned criteria and analysis. If the score exceeds a certain threshold, the email is classified as spam and redirected to a spam or junk folder.
Types of spam filters
Spam filters can be of various types depending on their deployment and the factors they evaluate. Let’s take a look at the different types of spam filters.
Types of spam filters based on deployment
1. Gateway spam filters
These are physical servers that have been positioned at the border of the organization's network. They operate as the first defense layer in preventing spam from a mailbox provider. Depending on all the incoming emails, this filter learns what to classify as spam. But on the flip side, it has less email information to learn from than in a hosted spam filter.
2. Third-party (or hosted) spam filters
Some companies have developed a standardized method of using content and credibility metrics to differentiate spam from valid emails. These third parties incorporate the technology to run hosted spam filters. However, the client still maintains complete control over their filtering practices.
As these spam filters have a massive customer service list, they also tend to have a broad array of data to evaluate whether to send a message to the inbox, spam, quarantine folder, or block it entirely.
3. Desktop spam filters
They are a type of third-party spam filter that exists on the end user's computer. They are customized to fit just right for the customer and are among the more difficult filters to pass through. These specialize in eliminating spam hookup emails containing 'adult' content and can be activated for underage children's security.
Types of spam filters based on what they evaluate
These types of filters analyze various aspects of an email and then filter out the spam. Below are a few spam filters, each specializing in a specific arena.
1. Content filters
These filters check the content inside your emails to determine whether they are spam or not. They examine every part of the message, including the subject line, footer, links, and images.
A few quick guidelines to avoid encountering the content filters are:
Avoid using shortened URLs in emails
Avoid overusing images and links
Proofread your content for typos or grammatical errors
Avoid 'spammy' or triggering words like free, donate, etc.
Personalize your emails
2. Rule-based filters
Rule-based filters work by using a set of ranking rules and filtering the content based on these rules. Usually, any received message score is zero. Then the email is sent for analysis to detect if it has an already existing rule. If it does, then the weight of this rule is added to the final score. But if the final score surpasses a specific threshold, it is filtered as spam.
3. Bayesian filters
A Bayesian filter can tailor itself to your preferences by analyzing the emails you classify as spam. It studies the content of the emails you mark as spam and uses this information to establish rules. These rules are then used to evaluate and filter future emails attempting to enter your inbox.
4. Blocklist filters
Blocklist filters prevent spam emails from senders whose IP addresses appear in any of the well-known blacklists, such as Barracuda, PSBL, and others. These filters are regularly updated to counter spammers who frequently change their email addresses.
5. Header filters
Header filters examine email headers to verify if they come from a trustworthy sender. This involves examining the metadata of emails, such as sender information, subject line, and routing details, to detect and block unwanted or suspicious messages.
6. Language filters
Spammers frequently send emails to people worldwide, occasionally using languages different from the recipients' native languages. Language filters are designed to block such messages. However, businesses with an international customer base may find that legitimate inquiries from customers in other countries could inadvertently end up in the spam folder. Therefore, it's advisable to regularly check the spam folder for expected messages from global customers.
How can spam filters help you as a sender?
Spam filters are not present to create obstacles in your path but help you in the long run. They filter out irrelevant, unsolicited emails, thus clearing out space in recipients’ inboxes. This ensures less competition and better inboxing for you in a sea of emails.
Adhering to the sender guidelines set by spam filters makes you a better sender and ensures improved email deliverability and sender reputation. Additionally, you can improve the performance of your email campaigns by providing relevant content to the targeted recipients.
Spam filters not only protect your recipients from spam but also safeguard you against cybersecurity attacks like impersonation, spoofing, phishing, etc. They shield you from DoS attacks, Business email compromise (BEC), etc. and take care of sensitive customer data.
How to safeguard your messages from being filtered
The first and foremost thing to take care of while steering clear of the spam folder is to read the spam filter policies thoroughly. Here are some basic rules to follow.
1. Gather consent
Make sure to send emails only to those people who have consented. This practice is essential for maintaining transparency, complying with privacy regulations, and fostering trust between users and organizations.
2. Warm up your domain
If there is a spike in the volume or the frequency of the emails you send, it can trigger spam filters and mark your emails as spam activity. You must start with a small volume of emails and gradually increase it over time. By doing this, you demonstrate consistent, legitimate sending behavior. This helps establish trust, reducing the likelihood that your emails will be flagged as spam and improves deliverability.
3. Authenticate Your Email
Implement email authentication protocols such as SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). These help verify that your emails are legitimate and that you care for the security of your recipients.
4. Maintain list hygiene
Build your email database from scratch to avoid sending emails to wrong, inactive, or deactivated email accounts to minimize your bounce rates.You can use methods like sunset policy, and suppression list to maintain a list with only active users and remove inactive and unsubscribed users periodically, leading to a healthy and clean email list.
5. Send quality content
Your content is the highlight of your email message. So, ensure that your emails are of high quality and engaging. Do not overuse images and links. Personalize your emails for an improved user experience and engagement.
Opt for interactive content that bolsters engagement and interactivity. You can also use AMP-powered interactive emails to allow your recipients to take actions within the email.
6. Activate whitelist
Send your customers a personal email (without any advertisement or marketing links) and ask them to whitelist your email. You can ask them to do this when you send them a welcome email after they’ve given you consent to receive emails. If you have been blacklisted from an account, personally communicate with them to get you out of there.
7. Test your emails
Send emails to various popular email providers like Gmail, MSN, Hotmail, Yahoo, etc., and check your deliverability. You can also use a spam filter checker to get a thorough analysis before you send out your emails. It helps in spam email removal if the emails contain any element of spam.
8. Follow sender guidelines
Follow the sender guidelines put forward by Google and Yahoo. It highlights the best practices that you should follow if you’re a bulk email sender. It includes practices like providing a clear unsubscribe button within the email and processing unsubscribe requests within 2 days.
9. Use email analytics
Use email analytics to better understand how your emails are performing. Keep an eye out on metrics like open rates, bounce rates, etc. Once you get insights on this, take the required steps to fix any issues that might be causing negative results.
Conclusion
Navigating through spam filters can be challenging, but it is crucial to invest the effort to ensure that your email campaigns effectively reach your desired recipients.
Spam filters play an important role in protecting organizational networks and email systems from cybersecurity threats like phishing, spoofing malware, etc. thereby enhancing email security and reducing potential risks to the organization. Additionally, they also help in better management of inboxes making it easy to keep track of important stuff.
Hence by adhering to the best practices mentioned in this article you can safeguard your emails and ensure that you reach your recipients effectively leading to improved email deliverability and sender reputation.
