7 Key Strategies for Avoiding the Gmail Spam Filter

How can you ensure that your legitimate emails aren’t marked as spam? In this article, we zero in on how to avoid the Gmail filter. But keep in mind that many factors can impact your email deliverability and include:

Now on to the specifics of the Gmail spam filter. Enjoy!

Are your email messages consistently reaching your subscribers’ inboxes? Or do they often get caught by the junk filters of web-based email services, such as Google’s Gmail, and land in spam folders? If many of your subscribers are using a Gmail account — which is likely because there are more than one billion active users worldwide — we provide some key strategies to help you avoid Gmail spam settings and filters. Plus, you’ll likely find these tips and tactics are useful not only for the Gmail spam filter, but also how to avoid spam filters for other web-based email services.

How Do Spam Email Filters Work?

No matter the organization, many email marketing campaigns find themselves circling back to the basic questions: how spam email filters work and why do some emails go straight to spam?

The way different spam email filters work varies. Most webmail providers use their own internal algorithms and metrics to determine a spam score and conduct email filtering. However, your email sending reputation, the quality of your email content, and your subscriber engagement all have a significant impact on whether your emails are classified as spam.

To help ensure webmail providers don’t report spam email for your campaigns, be sure that you are using proper email authentication and that your sending Internal protocol (IP) reputation is good. In terms of email authentication, Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) are the major standards used by most Internet service providers (ISPs) and spam filter providers. Furthermore, your sending reputation is also determined by a number of factors, including blacklisting, bounce rates, spam complaints, and a lack of sending IP history.

As far as content, avoid email formatting that indicates your emails are spam, such as:

  • Using a wide variety of font sizes (especially bigger than 12 point), styles, and colors
  • Using all uppercase letters
  • Including several links to different domains
  • Using exclamation points in the subject line
  • Using symbols and numbers to help spell words
  • Including too many large images.

Maintaining a high-quality email list is also key to getting through spam filters. If you send email campaigns to invalid email addresses or to prospects and customers who are consistently ignoring your emails, your email reputation and deliverability will suffer.

How Does Gmail Determine an Email Is Spam?

Gmail’s junk mail algorithms and user-created Gmail forwarding rules are quite effective at auto filtering unsolicited emails and unwanted junk email, and delivering them to recipients’ spam folders. Unfortunately, there are times when legitimate emails are marked as spam, even though the subscriber wanted to receive them. Although email services such as Gmail don’t share the exact algorithms for deciding if an email is unwanted by intended recipients, the following are some of the major reasons why an email may be marked as spam or why rules in Gmail may result in a message automatically being blocked:

  • Content — Typically one of the least common causes for pushing an email to the junk box, certain words or phrases found within messages and subject lines can cause them to be caught in a spam filter.
  • Links — If a message includes links to websites that are blacklisted, they could result in the message being caught in an email spam filter.
  • Source — If other email messages sent from the same IP address that you use appear to be spam, your emails may be categorized that way, too. In other words, it’s guilt by association. This can become a problem for small email senders who may be on a shared server.
  • Headers — If there are inconsistencies in the “from” and “reply to” addresses and domains, emails will be filtered as spam.
  • Engagement — Recipients who know how to create rules in Gmail can manage filter settings and deliberately label certain messages as spam; however, engagement metrics, such as open and click-through rates, also can affect the email-filtering process. An increasing number of Internet service providers (ISPs), including Yahoo! and Gmail, are using such engagement metrics to determine if an email should automatically delete spam email, or be blocked or filtered as spam. In effect, Google is simply trying to provide a great user experience, just as Google’s search algorithms do. So, Google views engagement metrics as an indicator of whether or not the user is interested in emails from an approved sender list. We have seen tests where lists with high levels of engagement get through Google spam filters, while lists without the engagement don’t get through.

Do You Have a Gmail Deliverability Problem?

How can you tell if you’re having deliverability issues with your Gmail subscribers? One way to detect a problem is by comparing the open rates of subscribers using other email software or services, such as Yahoo!, Hotmail, or Microsoft’s new Outlook.com. If the average open rate of an email sent to Yahoo! subscribers is 30%, for example, and only 5% for Gmail subscribers, it’s likely your emails are going to Gmail spam folders instead of the inbox.

How to Prevent Emails From Going to Spam

How to avoid spam filters when sending emails is vital for any marketing or sales team to know. The following are some important strategies and spam filter testing tips to help you get into Gmail’s inboxes and prevent deliverability problems in the future:

  1. Check the content of your emails. If you have a deliverability issue, check to see if the content is to blame. Start by sending a neutral message to a Gmail address using your existing sending infrastructure including the “from” address, sending domain, and IP address. If it doesn’t get filtered to Google junk mail, break up the copy of the problem email and be sure to send it in pieces to determine if the problem is located in the subject line or message copy. And keep in mind that it could be an image or a link that’s causing the deliverability issue.
  2. Tell subscribers to watch for your email messages.  Emails to confirm a purchase or new subscription are among the most opened emails. So use them to tell your subscribers to watch for upcoming emails and to check their spam folders if they don’t receive them. It’s possible users may have created an email rule or spam filter that either blocked or marked your content as spam.  You may also want to remind them how to set rules in Gmail and to let Google know your emails are wanted by clicking the “not spam” button if they do find your emails in their Gmail junk folders.
  3. Ask subscribers to add your “from” address to their Gmail list of contacts. This will help ensure that your emails don’t suffer Gmail automatic forwarding to recipients’ junk folders.
  4. Keep track of your engagement metrics. Are your subscribers opening and clicking your emails? Or do they skip and delete your emails without opening them, unsubscribe, or report them as spam? Gmail uses such engagement metrics to determine whether its users want your emails. So if your subscribers are inactive — i.e., if they haven’t opened or clicked your emails in a certain period of time, such as 6 months — you should consider running a reengagement campaign. In this way, you’ll identify the subscribers who aren’t interested in receiving your emails and can remove them from your list.
  5. Make unsubscribing quick and easy. How easy is it for people to unsubscribe from your email list? Is it a simple, one-step process? Is the unsubscribe link easy to find? Do you promptly respond to unsubscribe requests? If people can’t easily unsubscribe, they’re much more likely to report your emails as spam and hurt your email reputation.
  6. Create an opt-in subscription process. In fact, Google recommends using a double opt-in subscription process, which involves sending a follow-up message that each subscriber needs to respond to. In addition, Google recommends not using pre-checked opt-in check boxes.
  7. Consider using a dedicated IP address and private domain. This is an important way to help ensure compliance with Gmail’s authentication strategy. We discussed the important role IP addresses and domain names play in email deliverability in a previous feature. And when becoming a “new sender” with a new IP address, be sure to use an IP ramp-up strategy: Start by sending a low volume of emails and gradually increase the volume over several weeks.


Click here for additional information about Gmail’s guidelines for sending bulk emails.

Need to improve the deliverability of your Gmail messages? We have helped many companies solve their deliverability issues. If you’re having issues with your emails getting junked, the experts at FulcrumTech can help. Email us or give us a call at 215-489-9336 and get started today.

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1 Comment

  1. William Sydnes

    This is a great article! I was having problems having email delivered to Gmail and tried several of your suggestions with much success.

    Best regards,


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