• Best Practices

The Science and Art of Gmail Deliverability

Kate Nowrouzi
5 min read

Email remains one of the best channels for personal communication. On top of this, email is also the best way for responsible marketers to increase their ROI. It’s no secret as to why, considering that users receive up to 200 emails a day on average on both their personal and corporate email addresses.

That’s a lot of other businesses to be competing with every single day in the inbox. The competition makes it that much more important to use email properly to ensure that you’re doing all you can to help improve your deliverability and conversions.

But how do you properly send an email for better deliverability?

Deliverability is half science and half art, by which I mean that some factors of deliverability are more concrete than others. 

Here are the main elements to consider when it comes to email deliverability:

  • Domain alignment

  • Email authentication protocols, including SPF, DKIM, and DMARC

  • Permission to send marketing emails

  • Appropriate sending frequency

  • Mailing list segmentation strategies

  • Infrastructure segmentation, including IPs, domains, and subdomains

Let’s look at the art and science behind email deliverability in detail.

The science of email deliverability

With the science side of the house, answers are definite. Having domain alignment in the header (MailFrom, d=domain, and FromAddress) is a great first step at mastering the science of deliverability, but it doesn’t stop there.

Email authentication protocols also need to be set up to further build legitimacy in your headers. Setting up your SPF, DKIM, and DMARC records tell ISPs that you are who you say you are, rather than someone who could be spoofing a legitimate business. There isn’t a lot of wiggle room when it comes to these factors of deliverability, so setting them up correctly should be a requirement. 

The art of email deliverability

The artistic side of deliverability is more flexible and arguably more challenging. Back in the day, you used to be able to send out an email blast and reach everyone on your email list. Email blasts don’t work anymore because they don’t have any personality. Personalization is the crowning achievement in sending right now because your emails should be for your audience, not the other way around. 

But it goes deeper than content and email design when we think about the art of deliverability. When thinking about your email strategy, you need to consider three things: permission, frequency, and segmentation.


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Make sure that you are sending to people who have opted in to receive emails from you, or that you have permission to send to them in the first place. If you’re sending to people who haven’t given you permission to contact them, you are sending spam. The definition of spam might change over time, but that core value of permission and consent remains true. 


Sending your messages at the right time is critical to your deliverability, and no two senders will have the same sending frequency. For example, a job recruiting company and a party supply company should not have the same sending frequency. The job recruiting company could be sent as often as every single day, whereas the party supply company will only send seasonal messages. 

Your sending frequency will largely depend on your industry and user preference. To better your deliverability, give the power of sending frequency over to your audience, and ask them how often they would like to receive your messages. 


Segmentation plays one of the largest roles in your deliverability. When we think about building out segments for better deliverability, there are two kinds we need to consider: mailing list segmentation and infrastructure segmentation.

Mailing list segmentation is a common best practice that every sender should utilize. An example of good segmentation would be to break down a large email list into three segments – active, semi-active, and inactive. The active user list is comprised of users who have engaged with your messages in the last 90 days, semi-active in between 90-120 days, and inactive being 180+ days. Once you breakdown your list into these segments, we highly recommend that you remove the inactive portion since some of those addresses could now be spam traps. 

Infrastructure segmentation involves your sending IPs, domains, and subdomains. For larger senders, sending should be split across several dedicated IPs that separate your transactional emails from your marketing emails to preserve your IP reputation. A similar breakdown should be done for your subdomains as well. Your marketing messages shouldn’t interfere with your transactional messages, and you can break these down with subdomains to keep your domain reputation as pristine as possible. 

How does this all relate to Gmail deliverability?

Gmail inboxes generally make up over 50% of a marketer’s email list. Given that data, it’s highly advisable to set up your current sending infrastructure and strategy to maximize your deliverability with Gmail. That said, Gmail has a highly sophisticated email system, but we have a good idea about what works. 

We know that Gmail relies heavily on domain reputation, and this is largely due to most smaller senders being on shared IPs. While IP reputation is still important, a shared IP’s reputation reflects the sending habits of multiple senders, so the reputation isn’t accurate of each sender. Domains, however, are tied to one sender alone and speak to your individual sending practices and reputation. That is why it is so important to break down your sending into different subdomains so that your conflicting reputations won’t impact one another. 

Domain segmentation also allows Gmail to better categorize your emails into their different inbox tabs (primary, social, updates, forums, and promotions.) For example, if you have a subdomain dedicated to shipping notifications, those emails will show up under the Updates tab. 

Regardless of which tab your email lands in, your email is still landing in the inbox rather than the spam folder. There is a misconception about the primary tab only being the inbox, and there is no golden rule for landing in the primary tab. Attempting to land in the primary tab can do you more harm than good, as users don’t want promotions in that tab and will mark those messages as spam. Tabs were introduced to organize the high volume of messages coming into inboxes, and allowing them to work in your favor helps your chances of engagement. 

Gmail deliverability: no tricks only treats! 

Given that the holiday season is upon us, it’s important to take a hard look at your sending infrastructure and strategy. Make sure your configuration is done properly, and then take stock of the finer arts of deliverability.

Before you start sending your holiday emails, apply these best practices to optimize your Gmail email deliverability:

Happy holidays and happy delivering,



Learn about our Deliverability Services

Looking to send a high volume of emails? Our email experts can supercharge your email performance. See how we've helped companies like Lyft, Shopify, Github increase their email delivery rates to an average of 97%.

Learn More

Last updated on November 18, 2020

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