Avoiding deliverability issues with Gmail (and other ISPs)

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Over the past several years, Cheetah Digital deliverability experts have received numerous questions from clients that are eager to better understand Gmail’s deliverability valuation processes and methodologies. Gmail, as an email provider, has always struggled to satisfy senders and, more recently, senders have become increasingly confused and dissatisfied. Gmail claims that whether your email makes it to your customer’s inbox or is delivered to spam is determined by over 4,000 points of data in its systems. As overwhelming as that seems, there are really only two data points you need to worry about in order to maintain a solid reputation with Gmail and stay in front of your customer contacts. To avoid deliverability issues with Gmail, it is crucial to work on decreasing your email complaints and increasing your email engagement. Let’s talk about how you can do those two things.


Many marketers are still focused on volume, making sure to send their campaigns to “everyone” and collect email addresses from “everyone.” However, this can result in an unnecessary number of spam complaints, and those complaints are the number one factor that drive your emails to the spam folder. Resolving issues with Gmail starts here. There are a few things to consider and improve on to ensure your emails are reaching the right customers and that you are keeping spam complaints to a minimum.


The data collection methods that a marketer uses and the number of spam complaints that they receive are often directly related. If your email address collection methods aren’t clear or do not strictly define what the customer is signing up to receive and how often they are receiving it, you will likely acquire more spam complaints than you should.

Establishing explicit opt-ins for all points of data collection is a good rule of thumb to follow. It gives your contacts the option to sign up for your marketing program, while also keeping them informed on the types of messages they will receive and how often. Setting expectations for customers up front is crucial to running a clean program. Just ensure that when those expectations are set, you deliver on exactly what they signed up to receive.

Practices that are typically a concern:

  • Auto-opt-in web forms – this includes (but is not limited to):
    • Shopping cart conversions where a purchaser is not given any choice but to sign up.
    • Pre-checked auto-opt-in forms, either in a shopping cart or any other type of form.
  • Contests/Sweepstakes:
    • These are typically riskier types of data collection since most sign-ups only want to enter a contest. However, if done properly, it can provide an opportunity to grow your list.
    • These types of forms are typically auto-opt-in and do not give customers an option to decline being added to the organization’s marketing stream.
    • Most frequently, customers do not receive clear statements explaining that they will be marketed to.
  • Point of sale:
    • If done properly, this can be very effective.
    • This could also be fairly risky due to potential email address typos that can increase the amount of bounces a sender would receive.
    • Typos can also lead to spam traps which can have a tremendous impact on a sender’s reputation.
    • Many marketing teams incentivize their brick and mortar stores to collect as many names as they can. This can often lead to false practices, where stores begin purchasing email lists or typing in fake email addresses to hit quotas or receive bonuses.
  • Purchasing lists/Renting lists
    • It’s never allowed. Just don’t do it!

Some of these points of data collection, when properly set-up, can be very successful for growing a marketing list. Take for example, a contest form that not only allows a contact to enter the contest, but also has a separate option giving explicit consent to be added to the marketing stream.

At the end of the day, if the opt-in is honest, clear and sets proper expectations, a large majority of complaints caused by the sign-up process can be avoided.


Engagement is something that is talked about a lot lately, not only regarding ROI but also deliverability. The primary role of an email provider is to deliver mail that is “wanted” and filter out email that is considered either dangerous or “unwanted.” If engagement is low (under 10%) for a specific provider, they may view consecutive emails as unwanted. If that happens, you’ll likely see a higher amount of spam placement that can make matters worse.

The more spam placement you receive, the lower your engagement numbers will be since you will not be making it into the inbox any longer. This can create a snowball effect that is difficult to recover from.

Engagement ties directly to the amount of spam complaints you receive.

Relevancy and cadence

Targeting/segmenting your contacts rather than “batch and blasting” has always been a good practice.  You will not only stay much more relevant with your audience, but they will be less inclined to mark your emails as SPAM because what they’re receiving is exactly what they were expecting.

Cadence plays a huge roll here as well. Sending too much (more than expected) can result in higher complaints. Sending too little may result in the contact losing interest and can lead to an increase in complaints due to a contact’s lack of engagement and confusion on where to go to unsubscribe.

Targeting by last engaged

Sending emails to only contacts that are more likely to open your email will allow you to reap the marketing benefits long term. Our contacts at Gmail believe that a sender should remove or opt-down a contact when the contact hasn’t opened an email in eight months. Depending on cadence, if the organization was sending messages daily, this could mean that specific contact has not opened the last 240 emails they were sent.

Targeting contacts that have opened or opted-in within the last 365 days, for example, will increase your engagement rates and lower your potential spam complaints. When open rates increase and spam complaints decrease, your sending reputation will improve and allow you to stay in the inbox. We recommend you avoid sending to contacts that have not opened your email in two years, but staying under 15 months is typically a better practice with regards to Gmail inbox delivery rates.

Open rates that average above 12% at Gmail typically will not have to worry about the engagement portion, but why not make this a priority? The more you target, the more ROI you will receive and the higher reputation you will achieve with various ISPs.

Reputation today is all about quality over quantity.

It’s better to lose 25% of a list and reach 100% of your contacts than send to 100% of your list and reach 25% of your contacts. Following the recommendations above will typically help most senders advance their reputations at various ISPs. For Gmail specifically, the above should be taken into practice rather than be seen as a recommendation since Gmail offers very little leniency when it comes to complaints and unwanted email.