Gmail Spam Filter: Vital Details Discussed

Dariia Leshchenko
Oct 31, 2022
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Email communication has reached another level of popularity recently. These days, emails are often used for personal and professional interaction. Thus they carry a lot of sensitive and vital information. Considering fraudulent possibilities, present-day spammers use the opportunity to steal confidential data and spread various malware through email messages. Such widely used email service providers as Gmail are forced to keep an open eye for spam emails to protect their users’ inboxes. Aside from that, any well-tuned Gmail spam filter can save your business reputation and improve the marketing campaign’s productivity. If you are new to the field, today we will discuss the notion of Gmail spam filters in detail so that you know what they are and how they work, not to mention how to customize them to your personal needs.

What is spam in Gmail?

Before we define the notion of the spam filter, you may want to know which messages are flagged as spam in Gmail. The emails that end up in the spam folder are often programmed to acquire your data or infect your device with malicious software. Once the system detects spam messages but can’t block them from getting into the mailbox, it puts them in the spam inbox so that the recipient is notified about the unreliable nature of the email.

What is a Gmail spam filter?

Sometimes, the Gmail system reacts to spam trigger words that the email contains but can’t delete them. These messages are sent to spam automatically to ensure that the reader is warned about potentially malicious activity. This is the primary task of the Gmail spam filter.

How does Gmail filter spam content?

There are a few approaches to spam filtering that Gmail features. The primary approach that the system takes is the sender’s email address verification. In case the incoming sender has been blacklisted before, the filter won’t let it through into your primary inbox. On top of that, the Gmail spam list includes a plethora of malicious links so that each message is tested against. If the system detects suspicious links, it will sort the incoming messages correspondingly. It is also possible to train spam filters to recognize specific words and phrases, errors, and mistakes.

How does spam work in Gmail: filtering rules

Not all the messages that end up in the spam folder are necessarily spam emails. The strict algorithm sometimes goes rogue and places a legit email into the spam box. Such an approach can backfire, both on behalf of the sender and the recipient. The sender won’t get another chance to correspond with a potential client since people rarely check their spam inbox. At the same time, a receiver will lose a potentially beneficial offer. To ensure that things like that occur as rarely as possible, you have to stick to the Google verification rules. They are the following:

Introduce SPF into the process – Sender Policy Framework is an email authentication protocol responsible for keeping hackers at bay. With an active SPF, it will be impossible to forge a fraudulent email from your domain address.

Work on the DKIM record – the DomainKeys Identified email is yet another security protocol. With its help, the system ensures that there have been no alterations to the message while in between the sending and receiving servers.

DMARC – Domain-based Message Authentication, Reporting, and Conformance is the third-based protocol that combines the efforts from SPF and DKIM to provide the highest level of security on the sender’s end.

If you implement all the primary DNS records into the process, you can rest assured that your messages avoid the spam folder and arrive directly in the primary inbox. You can run a dedicated email deliverability test to see how many of your emails go to the spam box and are sent to the main inbox.

How to create a spam filter in Gmail?

Now that you know how to avoid the email spam folder, you may need to know that it is possible to create your spam filters so that your primary inbox is 100% safe. There are a few simple steps to take:

  • Sign in to your Gmail account.
  • Press the Settings button.
  • View All settings.
  • Find the section Filters and Blocked addresses. Click the option.
  • Press the Create a new filter button.
  • Type in the sender’s address in the From field so that emails from a given sender don’t go to the spam box.
  • Create the filter.
  • Click the Never Send it To Spam button.
  • Finalize the creation, and you are all set.

Can you customize a Gmail spam filter?

Now that you know how to create a Gmail spam filter, you may wonder whether you can customize an existing filter. It is possible to disable the Gmail spam filter, but you may want not to rush with the option and start with customization first. Here’s how you can do it:

  • Get into the Admin console.
  • Find the advanced Settings. Start with Apps, proceed to G Suite, Gmail, and Advanced settings.
  • Choose the organization.
  • Locate the Spam section and press the configuration button.
  • You can choose a more aggressive filtering approach or allow some messages to bypass the filters if you trust the sender.
  • Use an existing list or create a new one.

‍How to add domains and addresses to the spam list?

The moment you spot spam activity, you can take immediate precautions and add the suspicious domains and addresses to the Gmail spam list. Here’s how you can do it:

  • Log into your account.
  • Find a list name you are worried about and pint over it until you see the Edit option.
  • Once in the Edit mode, you should type in the addresses and domains you want to filter out.
  • Save changes when you are through.

How do you disable the Gmail spam filter?

Despite how effective spam blocking is, the Google spam filter sometimes sends the wrong messages to the folder. At times like this, you may wonder how to switch the filter off.

  • Sign into your Gmail account.
  • Find the Settings button in the top-right corner of your screen and click it.
  • Proceed to the All Settings section.
  • Open the Filters and blocked addresses tab.
  • Create a new filter.
  • Locate the Includes the words section and type in in:spam phrase.
  • Create a filter with this search.
  • Press the Ok option.
  • Find the tab Never send to spam and click on it. Such an approach ensures that whenever the system feels like flagging incoming messages as spam emails, but you’ve chosen to accept them, they will show in the Primary inbox.

Why is my Gmail spam filter not working?

There are situations when the Gmail spam filter allows all the spam messages into the main inbox. You should approach the matter with all caution and try to solve it as soon as possible. Usually, there can be two reasons why the spam filter misses potentially dangerous emails.

  1. Compromised Gmail account;
  2. Gmail does not sync.

The first case scenario is not very common nowadays, but exceptions happen. Here’s what you can do to fix the problem:

  • Change your Gmail password.
  • Sign into your account.
  • Press the See all settings tab.
  • Proceed to the Filters and blocked addresses section.
  • Create a new filter.
  • Type in the addresses of the email you want landing in spam.
  • Save the changes and monitor if the issue persists.

Another reason why your spam filter malfunctions is that Gmail does not sync. You should start by checking whether the Skip the inbox filter works correctly:

  • Log into your account and go to Settings.
  • Choose All settings.
  • Pick the Inbox tab and scroll down.
  • In case the Override filters tab is checked, you will receive the emails that you have set the filters for.
  • If you want to fix the issue, press the Don’t override filters tab.
  • Save changes and watch if the matter is solved.

How to avoid emails going into spam?

Why are my emails being sent to spam? That is the main question to answer if you want to keep clear of the Gmail spam filter. There are a few primary triggers that alert the filters. Let’s discuss all of them in further detail.

Missing authentication

As has already been mentioned, authentication protocols can vouch for the legitimacy and reliability of your emails. That is why it helps to check whether your SPF, DKIM, and DMARC records are intact. You should realize that when a spam filter does not recognize the sender’s credentials, it won’t put the recipient at risk and automatically send your email to the spam box.

Questionable content

The main aim of your letter is to notify the reader about something important. That is why the quality of the content you share in the email is critical. Make sure that there are no grammatical, punctuation, or spelling errors. It helps to eliminate the spam-trigger words from the text as well.

Cut short on attachments

It’s proven that spammers use attachments to infect people’s devices with various viruses and steal their critical data. That is why the spam filters will become alert if you introduce too many attachments to your message. It is best to use useful links and documents instead.

Check your domain name

Your domain name can be added to one of the existing blacklists without you even knowing it. A Gmail filter will mark any messages coming from you as spam should you appear on such a list. Thus, you should run a blacklist check every now and then to rest assured that your domain name is clear.

Watch out for the headers

It is easy to underestimate the role of email headers, but they are often critical. The truth is that hackers may alter the headers to share their malicious content with your user base. If you notice that your headers have been modified, it is advised to change the email client so that you don’t end up in spam.

Final words

The notion of Gmail spam filters is more complex than one dares to assume. While it is a blessing, it can also turn out to be a curse if you don’t address the matter correctly. Now that you know why you need to create a Gmail filter and how to customize and disable it, you will be able to control your inbox more profoundly.


How does Gmail filter spam?

Gmail filters all incoming emails automatically to divide legitimate emails and spam messages. Certain algorithms are encoded in the system to respond to specific words, phrases, attachments, and other indicators.

Can I create a custom Gmail filter?

Yes, you can. You will find more information on the matter in the Can you customize a Gmail spam filter? section.

 Why are my emails being sent to spam?

There are different reasons why legitimate emails may end up in spam. Try to keep away from spam-trigger words and stick to authentication rules to have your emails directed to the primary inbox.

Dariia Leshchenko
Dariia Leshchenko
Customer Success Manager
Dariia's decades in Email Deliverability and Sales have allowed her to successfully manage diverse business clients. For years now, she proves that there are no issues not to be fixed. Dariia speaks for the synergy of new-level email analysis technology and a human approach to improving email performance.