Five Best Practices For Email Deliverability

Five Best Practices for Email Deliverability

We all agree email marketing is one of the top drivers of customer engagement, yielding the highest potential ROI of all marketing channels. We continue to see enterprise businesses investing more and more into email marketing, but are they optimizing their email efforts to improve deliverability?

With ReturnPath’s studies on email metrics, they show that read rates continue to drop annually and more messages are hitting the spam/bulk folder. Contrarily, they also found more consumers were marking promotional email as “Not Spam.”

Most ISPs (internet service providers) utilize machine learning to determine how they should filter inbound mail. Their primary goal is to ensure their users are happy, by delivering “wanted” mail to the inbox and keeping everything else out — whether it’s never delivered or filtered to spam. So it’s not necessarily that users aren’t engaging with email as often, but rather that ISP filters are becoming more aggressive — often filtering messages that users want to see in their inbox to the spam folder.

So as a sender, what are some best practices to follow to ensure your marketing emails are hitting customer’s inbox?  

Subscriber list development

Businesses should always build out their subscriber list organically, acquiring addresses of subscribers who opted in to receive promotional messages. It’s surprising how many business still purchase lists and append their data using third parties, which undoubtedly hurts your sending reputation and deliverability. It’s important for marketers to understand that higher volume doesn’t necessarily mean higher ROI. Sending to purchased lists will drive high hard bounces, complaints, and trap hits — all facets that can seriously hurt your deliverability. Building your email database the right way will help keep engagement high and emails in front of the consumers that matter. 

List/Data Hygiene

Even though you have organically built out your email subscriber list, this doesn’t mean deliverability and engagement will remain high. It’s also important to manage and clean your data consistently — removing hard bounces, complaints, and unsubscribes. Many consumers will simply sign up their email to receive a one-time promotion/discount on a product. It’s also common for consumers to sign up fake or fat-fingered addresses, which commonly end up being a bad address (hard bounce) or, even worse, a spam trap. Users who have opted in to your program a year or two ago may not be interested in your emails now, or even remember signing up in the first place. Segmenting your subscriber list by engagement and removing unengaged users on a regular basis is a great way to maintain strong deliverability. 

Sending frequency and Cadence

It’s important to maintain a consistent sending frequency and cadence so users have expectations for your emails. ISPs are also considering this when looking at sending reputation. When a user signs up for your emails, sending a triggered welcome message is a great way to remind users why they signed up. While we want to maintain a consistent sending frequency and cadence, we shouldn’t be flooding consumers’ mailboxes. Setting up a preference center, allowing users to control the amount and type of emails they want to receive from a brand is a powerful way to limit complaints/unsubscribe rates. Sending multiple emails to consumers daily without any call to action can drive high unsubscribes and complaints, ultimately hurting overall deliverability. 


Segmenting by engagement is a good way to start generating better inbox placement and engagement metrics; personalizing emails can boost that even further, though. Factoring in subscriber information like location, age, gender, purchase history, and browser behavior will help bring a better sense of relevancy to your emails. Optimizing the times email campaigns are sent is another great way to ensure messages aren’t missed and help keep engagement high. Essentially, the more you cater your emails to your subscribers, the more likely you are to reach and resonate with them.  


The rate at which consumers are reading emails on mobile devices continues to rise. A study by Litmus showed more than half of email opens were done on a mobile device rather than the traditional desktop. Ensuring your email templates render properly on all mobile devices and have a responsive design is crucial to keeping users engaged. A poor user experience could mean no response, no action or, in other words, no ROI. 

While the list can go on and on, these five points discussed above are great ways to start optimizing your email marketing efforts and helping your messages get past the increasingly aggressive ISP spam filters.

Albert Liu

Albert is the Head of Deliverability at MessageGears and responsible for helping clients optimize their email marketing efforts. He is the primary contact involved in on-boarding and consulting with clients, as well as managing ISP escalations/relationships. He knows all the ins and outs of deliverability and wants to help businesses understand how to enhance their email marketing campaigns.

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