Deliverability 101
How to avoid landing in spam

Deliverability can make or break your email strategy - it dictates whether your customers see your emails or not. In this guide, we’re diving deeper to give you the full breakdown on deliverability, and how you can ensure emails hit inboxes long term. Email deliverability can be an ominous subject — that’s about to change.

What is deliverability?

Email deliverability is based on your sender reputation, domains, and ips.

Email deliverability is essentially whether your emails are landing in subscribers’ inboxes. To have good deliverability, you need to have a good sender reputation.

What is a sender reputation?

This is what internet service providers (ISPs) like Gmail and Outlook keep track of overtime to decide whether they’ll filter your emails to the inbox or spam. Think of it like a graded track record of your email behaviour: if you consistently get As, your emails will hit inbox. If you get subpar grades like Bs or worse, your deliverability will fluctuate and it will become harder to earn an A+ reputation, lowering the chances of your emails continuously hitting inboxes.

How is sender reputation determined?

ISPs tie your reputation to your domain and the IP your email goes out on, with most consideration placed on your domain reputation:

Domains & subdomains

A domain is a unique identifier of your website (for example, ISPs mainly take into consideration the sending history of your domain when determining your sender health, as this is the most accurate and holistic track record that is unique to each sender.

When using an ESP, your emails are sent over shared domains (i.e. that already have a reputation built, until you set up a custom domain. Many brands are quick to set up custom domains since it lets them choose the sender email their subscribers see. When choosing a custom domain, it's highly recommended that you set up a subdomain if this is an option on your ESP.

Subdomains mitigate the risk of ruining the reputation of your root domain - an irreparable act. A subdomain is a subsection of your root domain. You can think of a subdomain as anything that comes immediately after the @ symbol as illustrated below.

Each subdomain you use gives you a separate reputation. It’s important to isolate different types of emails on different subdomains, especially if your brand sends a high volume of email. This eliminates the risk of an email mistake getting your main domain blacklisted by ISPs, and ensures that the deliverability of your marketing emails (promotions, new releases, etc. that typically get lower engagement) don’t hinder that of your transactional emails (think: order receipts, shipping notifications, password resets).

"Every subdomain has a separate reputation.

Because ISPs view each subdomain separately, it’s important to properly warm up and maintain each one to optimize for long term deliverability.

IPs: shared & dedicated

IP addresses are what your emails are sent over. Every ESP has a set of shared IPs your emails are sent on, unless you choose to have your own dedicated IPs. Each IP address is scored individually by ISPs based on the quality of emails that have been sent over the IP in the past.

Shared IPs

A shared IP is an IP that your ESP manages in the backend to ensure good deliverability.

Every ESP has a shared IP pool that emails are sent over. ESPs are responsible for the technical infrastructure and maintenance required to ensure emails are delivered smoothly on these IPs, from setting up feedback loops with ISPs to maintaining the sending volume necessary to keep IPs healthy.

For most email senders, it’s best to use shared IPs as long as the ESP you work with takes proper care of their shared IP pool and screens out bad senders. A good ESP will delegate your email sends over various IPs based on subscriber engagement, in order to healthily build the reputation of your domain. By separating out emails of your highest and lowest engaged subscribers across IPs, the risk of your bad subscribers affecting the deliverability to your good ones is lowered. The key to ensuring your emails are sent over the best IPs is to make sure your subscribers are actively engaged.

Dedicated IPs

A dedicated IP is an IP that you’re responsible for managing to ensure good deliverability.

Dedicated IPs are only essential for high volume email senders, as it allows the health of these IPs to be isolated to a specific domain (no other senders will affect your deliverability if you use dedicated IPs). However, switching brings on a slew of additional tasks that most email senders can’t keep up with and frankly shouldn’t need to.

"Dedicated IPs are a myth, usually.

Often, email senders switch to dedicated IPs as a quick way to resolve deliverability issues without realizing what it takes to maintain the health of these dedicated IPs, resulting in poor deliverability once again. For many email senders, optimizing your email strategy will always lead to better deliverability results than switching to dedicated IPs, especially in the long-term.

Sender Reputation

So, we know that your deliverability is tied to your sender reputation. How do ISPs actually determine your sender reputation and inbox placement? Let's dive in.

How to build a strong sender reputation

The ideal sender is one that sends a consistent volume of emails with high engagement.

As Sparkpost says, “User engagement with emails matters more than ever. It’s the key factor in deliverability - and your success”. Your sending frequency and subscriber engagement are the two main factors that ISPs take into consideration when scoring your sender reputation. To them, the ideal sender is one that sends a consistent volume of emails with high engagement, on a frequent basis.

consistent volume + high engagement + frequent basis =
strong sender reputation

The key to building a strong sender reputation is having a holistic email strategy centered around consistently sending good emails your subscribers engage with. ISPs consider the following types of engagement as “good”, which help build your sender reputation:

  • Opening your emails

  • Clicking your emails

  • Replying to your emails

  • Forwarding your emails

  • Marking your emails as ‘Not Spam’

  • Moving your emails to a folder

  • Adding your sender domain to their address book

The more of these positive engagements your subscribers continuously take, the stronger your sender reputation becomes. In contrast, you don’t want subscribers to do the following, as these will hurt your sender reputation:

  • Marking your emails as spam

  • Not opening your emails

  • Not clicking your emails

Think of how you use your personal inbox every day (whether it’s Gmail, Outlook, or another ISP). You’re reading emails, clicking links, archiving things you don’t care about, and marking the odd something-you-definitely-don’t-remember subscribing-to as spam.

What you might not be thinking about is all the signals you’re sending to your ISP. As you go through your inbox every day, your ISP takes note of what you open, what you don’t, and what you click on. They use these signals to dictate what will get top inbox placement for you in the future - maybe you’ve seen the newsletter you engage with every day move from Promotions to Primary, or maybe you’ve noticed those marketing updates from a brand you haven’t bought from in over a year in your spam folder.

If you start thinking of all your subscribers in this light, you’ll get a better idea of what you need to do to improve deliverability. Actively thinking about each of your subscribers’ inboxes incentivizes creating emails that you know your subscribers will engage with, and disincentivizes emailing inactive or poorly targeted subscribers.

How to avoid the spam folder

These best practices will guarantee better inbox placement for your strategy. Simply follow these tips and you'll build strong deliverability for your brand in no time.

Best practices for strong deliverability

Strategies & tips for landing in inboxes and avoiding the spam folder

How do you get subscribers to interact and engage positively with your emails? Here are best practices you should incorporate into your email strategy:

Clean your list

Prune out invalid and unengaged subscribers

It’s common sense - if ISPs favor senders with consistently good emails that receive high engagement, you’ll only hurt your deliverability by continuously emailing subscribers who never open your emails. Cleaning your list helps protect your deliverability, especially in regards to the subscribers that regularly open and click your emails. Bonus: knowing the state of the subscribers in your list will help you come up with an intentional strategy to re-engage inactive subscribers.

Isolating your inactive subscribers will help you hone in on the best way to engage them (think, what’s the one email you can send that will instantly get them to open and click through). You’ll also want to manage list hygiene by constantly pruning out invalid subscribers (unsubscribes, hard bounces or spam complaints) as these are people you never want to email - a good ESP will often have this built into their product.

Hive automatically buckets your contacts into engagement levels: actives, new subscribers, at-risk, inactives, and invalids, making it easier for you to send core campaigns to your active subscribers and strategically email subscribers in other levels. Subscriber engagement levels update in real-time based on how they’re engaging with your emails, giving you the most accurate and comprehensive view of your list.

Worship welcome and winback email automations

Engage your new and unengaged subscribers strategically

The most effective way to immediately engage new signups and re-engage anyone who’s fallen off is with welcome and winback automations. These are email campaigns designed strategically to appeal to new and unengaged subscribers, set to automatically trigger based on a certain action (e.g. upon signup or after a user hasn’t engaged with 5+ emails). As a result, these emails are sent at exactly the right time with the relevant content necessary to engage subscribers.

Welcome campaigns

A welcome campaign is the first email or series of emails a new subscriber gets, triggered upon signup. ISPs look at these emails to see if a subscriber wants to hear from you, which makes it a crucial time for good engagement. These subscribers just signed up to your list, which almost guarantees that they will open the first email you send them. Welcome emails are proven to be the most engaging promotional email with a whopping 84% average open rate, making them a valuable opportunity for you to establish a strong sender reputation. You don’t want to miss this in your email strategy.

Tip: Include a double opt-in in your welcome email by placing a ‘Confirm Subscription’ button above the fold. Subscribers will likely click through, signaling to ISPs even further that future emails from you should land in the inbox.

Bonus Tip: Replies are even better! Consider posing a question in your welcome email asking subscribers to reply with an answer, their preferences, or feedback. You can also try including a contest in your welcome series where subscribers reply as their entry.

Winback campaigns

A winback campaign is an email or series of emails sent to a subscriber who hasn’t engaged in a set period of time. Designing a relevant campaign to winback your at-risk and inactive subscribers will increase the chances they’ll actually engage. Remember, lack of engagement kills your deliverability, so make sure your winback email includes enticing content that your unengaged subscribers will actually click on.

For most brands, a simple ‘We miss you’ or ‘Still want to be on the list?’ is relevant enough to re-engage at-risk and inactive subscribers. If you’re an ecommerce brand, you may want to include a discount code to drive higher conversion. If a subscriber goes through your entire winback automation without engaging, it may be time to prune them from your list and consider them invalid (or at the very least, be very cautious when deciding to email them again).

Send targeted and relevant emails

Segment subscribers and keep emails relevant

You should know by now that blasting your whole list is a recipe for disaster - especially for your deliverability. Even when emailing your active subscribers, you should segment based on interests, demographics, purchase behaviour, etc. This lets you design campaigns that are hyper-relevant, increasing the chance that they’ll continue to engage. Targeted emails are shown to have 82% higher open rates than bulk email blasts, further proving that segmentation is a must in any good email strategy.

"Segment your active subscribers to maximize engagement.

What happens if you don’t segment? The chances that all your active subscribers will find the same email relevant is null, so continuing to send the same emails will only cause more and more of them to drop off. Over a period of time, ISPs mark you as a bad sender due to lack of engagement. This is what will land your emails in spam, even for engaged subscribers.

Design emails for engagement

Optimize your email template for clicks and replies

Imagine you go through all the work of building a smarter email strategy, yet send a poorly designed email that no one wants to see in their inbox. This could lead them to unsubscribe, stop opening your emails or worst yet, mark your email as spam. Designing emails for engagement is a critical step in keeping your relevancy in subscribers’ inboxes, and driving opens and clicks.

Manage your sending volume overtime

Send a consistent volume on a regular cadence to maintain your sender reputation

ISPs are on the lookout for suspicious activity which includes erratic spikes in sending volume. To maintain a healthy sender reputation, you should send approximately the same number of emails on a daily basis. Let’s say you have a weekly newsletter that you send to 800k subscribers every Wednesday. If you aren’t sending quality content to these 800k subscribers every day, it’s best to break that down into chunks of 200k subscribers that you email 4x a week.

Due to content schedules and required timing, we know this isn’t always possible - if you can’t break up one large email over multiple days, your best bet is to have other campaigns to send out to smaller segments between your weekly campaign to mitigate the spikes.

It’s also important to ramp into high sending volumes, both for your domain and the IPs your emails are sent over. ISPs like to take it slow and steady when building a relationship with you as a sender (AKA playing the game of determining whether they’ll place your emails in inbox or spam). You want to prove that you deserve to send high volume email with good placement by ramping your volume overtime. Best practice is to start with a send of 2,000 subscribers and increase volume by 2x with each send on a daily basis. More on this coming up next.

Key learnings

Takeaways for healthy long-term deliverability.

Key learnings

The tl;drs to take away from this guide

To have good deliverability, you need to build a strong sender reputation. This is tied to your domain and IP pairing. It’s best to isolate your reputation by using subdomains. ISPs look for consistent good email engagement to determine that you're a good sender:

  • Opening your emails

  • Clicking your emails

  • Replying to your emails

  • Forwarding your emails

  • Marking your emails as ‘Not Spam’

  • Moving your emails to a folder

  • Adding your sender domain to their address book

To build a strong sender reputation, you need a holistic email strategy centered around consistently sending good emails your subscribers engage with:

  • Constantly prune your list

  • Set up welcome and winback automations

  • Send targeted and relevant emails by segmenting

  • Design emails for engagement

  • Manage your sending volume overtime

The following are deliverability don'ts, things that will hurt your deliverability and damage your sender reputation: 

  • Blasting your whole list

  • Sending infrequent big blasts

  • Using an ESP that doesn't take care of their shared IPs

  • Switching to dedicated IPs without properly maintaining them

  • Sending long emails with spammy content and too many links

  • Spam traps

  • Blacklisted domains

Deliverability 101 Webinar

Not a fan of reading? Us either. That's why we shared an entire breakdown in video format to watch whenever you please. Coming to a Netflix show near you.