How Do Spam Filters Work?

Author
Vladislav Podolyako
Published
04.22.2020
Reading duration
9m
Copy post
Sand via email
Save in Pocket
Save in Flipboard
Send in Messenger
Send in Messenger
Send in Whatsapp
Share via Facebook
Share via Linkedin
Share via Twitter

Email marketing provides a large ROI to over 59% of businesses. This is why around 93% of B2B processes are built on email outreach. Therefore, the quality of sales is based on the quality of email deliverability. And, as we know, your deliverability depends on your relationship with email spam filters. 

However, what shapes this relationship? Is it defined by email campaigns alone? There are a lot of complexities related to spam filters, and in this article, we’ll try to guide you through the basics that will help you plan your outreach without compromising your email deliverability. 

What is spam?

No, we won’t go back to the history of spam that starts with post-World War II canned ham. Everybody knows that part. Instead, we’d like to talk about the essence of spam. What is spam nowadays? Usually, we imagine it as a bunch of invasive emails that make no sense, are full of bright images and flashy gifs or messages that try to sneak .exe malware into your PC. Sure, this is a part of spam. Nevertheless, that’s not all. 

Modern spam includes more than those emails. Now, it also covers any emails you don’t expect or want to receive. For example: 

  • you receive an email from a company whose product or services are not relevant to you in any way;

  • you keep receiving the emails from the sender and you’re sure that you didn’t give your email address or any other personal data;

  • you don’t respond to this email but the sender sends you the same email again as if nothing happened;

  • you end up blacklisting the sender and flagging all his email as spam.

This is how most spam emails in B2B look like. They may belong to legitimate senders who use illegitimate means to reach their audience.

How are cold emails different from spam emails then?

The debate on whether cold B2B emails should be considered spam has been going on and on. On the one hand, cold emails are sent to unexpecting recipients. On the other hand, networking aside, cold emails are pretty much the only bridge between vendors and their potential customers. And, given that worldwide force-majeures can happen pretty much anytime, offline events and F2F meetings in the office or over the cup coffee won’t always be there to help you forge solid B2B relationships. 

In addition, there are several key differences that distinguish a cold email from a spam message: 

  • Targeting. Companies that send unsolicited emails aren’t very cautious with their research. They send emails to a large bulk of companies, which, speaking from the perspective of account-based marketing, don’t belong to A-tier or even C-tier accounts. Therefore, they end up with a high bounce rate and their Sender Score sinking below zero. Meanwhile, responsible cold email outreach never starts without a detailed prospect database. 

  • Volume. It’s normal for cold outreach to send over 2000 emails per day…to 2000 different email addresses. Meanwhile, spam senders can send approximately the same amount to the same email address. Spam filters are very sensitive to the number of emails sent from a domain. If it’s a freshly created email domain, it’s daily message limit is quite low. So, if this email domain starts sending over 1000 messages every day, spam filters start treating it with suspicion.  

  • Content. Typical spam emails lack self-awareness. When you read them, you don’t feel like the sender is talking to you exclusively or describes benefits that would work for your company. Cold outreach crafts and adjusts each template according to the needs and demands of a particular prospect. 

Now, with that covered, let’s talk about spam filters. 

How do spam filters work?

Spam filters run on software for scanning and analyzing emails for any potential spam triggers. Their analysis is based on several criteria. The more criteria the email meets, the higher is its probability to be labeled as spam. These criteria include: 

  • IP-address. It matters where emails come from. If they are sent from an IP address that used to have issues with the violation of the SPAM-CAN Act, uses an obscure or untrustworthy service, or has been added to blacklists, they will be instantly redirected to the spam folder.

  • Coding. Misuse or overabundance of tags, as well as bad coding, also alerts spam filters. This is why there are strict rules and regulations regarding images, files, and attachments. 

  • Data. Emails that indicate only the email address of the recipient without their name are more likely to be treated as spam by spam filters. Additionally, it also matters whether your recipients agreed to keep receiving emails from you or added you to their contact list.     

  • Patterns. More advanced filters such as Gmail spam filters go as far as exploring behaviors of each suspicious sender and comparing them with the behavior types observed among phishers and malware-spreading spammers.

Modern spam filters offer a large variety of advanced spam-blocking features. However, their complexity also means that sometimes innocent senders get caught in the crossfire. It often happens due to ignorance regarding the way spam filters work. For example: 

  • You may be unaware that your IP address was blacklisted. It requires a search across Domain Name System Blacklists or the use of special tools that do it for you in a matter of seconds. 

  • You don’t track your Open Rate. If your emails are left ignored by your recipients, it should be a huge red flag. At best, your subject lines may lack appeal and thus give your prospects no reasons for opening them. At worst, your emails land in the spam folder and therefore keep dropping your Sender Score without you being aware of it. 

  • You don’t pay attention to your content. Advanced spam filters examine every segment of each incoming email. That includes a header, a subject line, and the body text. In their examination, they refer to the constantly updated list of spam triggers — words that spammers usually use in their message. Those triggers range from something obvious and predictable like “buy”, “SALE”, “FREE” to more discreet options such as numbers or overabundance of exclamation marks.  

  • Your VPN settings lead to your emails being flagged as spam. Many businesses that work with clients across the globe use a virtual private network for extra security. However, that measure may impact their relationship with spam filters. VPNs use a rather short list of IP addresses. Major email service providers such as Gmail only recognize IPs featured in the database of mainstream VPNs. So, if you don’t use a popular VPN, you can expect to be flagged as spam. Moreover, mobile computing made things even more complicated. For example, if you send emails to a client who is currently staying in a hotel and uses a local Wi-Fi network, your emails may get redirected into a spam folder due to the hotel VPN following a no-log policy and being suspicious about everything that comes from an out of the area server.  

How to improve your relationship with spam filters?

Staying in the good graces of spam filters is not difficult. First of all, remember — they’re not the enemy. They do tons of work, every day, to ensure the safety of billions of mailboxes worldwide. If you get caught in their anti-spam measures but make your move at the early stage, you’re guaranteed to come out unscathed, saving your outreach campaigns and reputation. 

spam filters

  • Use reliable email services. Don’t try to tinker with email domain settings and VPN yourself. It will cost you time and sanity. Services like MailChimp are designed to handle your emails and are recognized by a large variety of VPNs, so by using them, you won’t have any difficulties with delivering an email. 

  • Get an email monitoring tool. Many outreach-focused companies have been paying attention to the situation and offering services that help businesses find a common language with spam filters. For example, Folderly is a new service that analyses several of your mailboxes and sends you a detailed report on each of them, letting you know your Sender Score, current performance, and understand how spam filters treat you. Additionally, it scans blacklists for your email domain just to be safe. 

  • Examine your emails. Your outreach content may look nice but email service providers see things differently. You can use services like mail-tester.com to quickly evaluate your email and see if there are any areas for improvement. This service creates individual mailboxes that you can send your email template to. After this, you receive a detailed analysis of your email structure that allows you to understand how your recipients’ email service provider would have responded to you. 

  • Don’t ignore unhappy recipients. Sales objections aren’t pleasant but they happen. Sometimes, you receive an email that says “Please, stop sending your messages or I’ll add you to the spam list”. When it happens, you do what your recipient asks and remove their email from your sending list. Don’t take such a threat lightly — it takes one click to bring your Sender Score down and you don’t want that. 

  • Provide your recipients with a way out. It’s generally recommended to ensure your target audience that they’re not trapped with you. When we send our Wave 4 emails to a recipient that didn’t respond to any of the previous waves, we indicate that it’s the last email we’re sending. In that last message, we only ask our recipient to give a short Yes/ No answer regarding our service. If we don’t get any response, we mark that recipient as not interested and move on. 

  • Know the capacity of your mailbox. Don’t send thousands of emails from a newly-created mailbox. Keep your mailboxes organized, develop new ones gradually by creating a schedule for sending emails. Gradually increase the number of daily emails. If you’re unsure whether you’re doing it right, you can always consult with an outreach expert who will help you organize and accelerate your mailbox at an optimal pace. 

Spam filters are amazing in what they do. When you know what makes them tick and how they’re triggered, you get a better understanding of making your outreach campaigns look presentable and valuable to email service providers. If you’re interested in learning more about spam filters and their ways of email analysis, we have a large How-To guide coming up.

To make sure you won’t miss it, subscribe to our blog and the update will fly directly into your inbox!

Vladislav Podolyako

Co-founder and CEO of Belkins and Folderly
Vlad’s decades of entrepreneurial wisdom and business building experience have allowed him to successfully mentor a diverse group of business owners, entrepreneurs in growing their companies. A recognized expert in the areas of transforming organizational culture and leadership development, B2B Sales, Marketing, spent more than 10 years building technology products, with a background in communication networks and electronic device engineering.

Also you may like

Why An Email Spam Test Is Necessary To Run Cold Campaigns
Why An Email Spam Test Is Necessary To Run Cold Campaigns
Anti-spam campaigns and anti-spam monitoring are often mentioned as part of Cold Email Campaigns. Let's see how you can solve deliverability problems.
Vladislav Podolyako
5m
What Is BIMI And How It Benefits You?
What Is BIMI And How It Benefits You?
A relatively new TXT DNS record, BIMI has all the potential to change things for B2B senders and B2B recipients. If you want to know what’s so special about the latest standard, dive in.
Vladislav Podolyako
5m