1. Email Deliverability Guide Part I: Mission Inbox-able
Email deliverability (aka inbox deliverability) isn’t yet a buzzword on the lips of every digital marketer out there. But it needs to be. Think about it. You work hard on your email marketing programs. All that work is wasted if your emails never make it to the inbox to fulfill their destiny. That’s why the best deliverability service team in the business came together to write this, The Best Email Marketing Deliverability Guide. Ever. Read on for chapter one.
2. Email Deliverability: What is it, anyway?
In simplest terms, deliverability is the overall health of a sender’s email program. You might have read online that deliverability is all about hitting the inbox. True: that’s the end goal.
But Delivery Rate is just one aspect of a holistic approach to email deliverability. Focusing only on delivery rate omits important aspects of your email program that contribute to your overall health and reputation as a sender.
A holistic approach to deliverability takes more than delivery rate into account. Before diving in, make sure you’re familiar with these common email marketing and deliverability terms.
Authentication
A process that confirms to ISPs that you are who you say you are, and that your marketing automation platform is sending on your behalf. Common authentication methods include DMARC, SPF and DKIM
Bounce
An email that cannot be delivered to the recipient’s email server.
Hard Bounce
An email that bounces because the address does not exist.
Soft Bounce
An email that bounces back for reasons other than a hard bounce (e.g., due to a full inbox or server outage). Soft bounces are often temporary, and senders can typically fix them.
Click Rate
Number of clicks divided by number of emails delivered.
Click-Through Rate (aka Click-to-Open Rate)
Number of clicks divided by number of emails opened.
Data Hygiene
The overall quality of your email list and the associated data. Effective email strategy, and strong deliverability, always rests on a foundation of high quality lists with the right information.
Delivery Rate
The percentage of emails that are delivered. Calculate it by dividing the number of emails delivered (total emails minus bounces) by the total number of emails sent.
Email Channel Health
Metrics like engagement, conversions, and even the ROI of your email program. You may be saying, “Isn’t that email strategy, not deliverability?” And you’re hitting on just the point we’re trying to make: you can’t separate solid email strategy from strong deliverability. And you shouldn’t try.
Inbox Rate
The percentage of emails that are delivered to a non-SPAM folder. It can be estimated, but as a sender, you’ll never know the exact inbox rate.
Open Rate
Number of emails opened divided by number of emails delivered.
3. Inbox Delivery: A Mystery Wrapped in an Enigma
Let’s start with a scene. A marketer walks into (or, more likely, joins us on Zoom) and meets with our Deliverability Team. They’re understandably eager to get started. They kick things off with what should be a simple question:
“What is my inbox rate?”
The Deliverability Team hesitates, knowing their answer is going to disappoint the marketer a little. They reply:
“We can narrow it down to a relatively tight estimate…but it will always be a mystery.”
The marketer looks confused. How can this be? They came here to get answers!
Well, today’s inbox is not what it used to be. For starters, what do you consider the inbox? The major ISPs (Inbox Service Providers such as Gmail, Yahoo! and Microsoft) all have their own way of filtering incoming emails according to the user’s expectations and customizations.
For instance, Google has its customizable tab system that includes categories like Inbox, Social, Updates and Promotions. Microsoft uses its own tab system divided into Focused Inbox, Promotions, Social, and Other. And of course, most major platforms offer users customization options to filter and route emails to their own subfolders.
Further, the ISPs use their own “bucketing” systems based on recipient behavior to route emails. These systems are opaque from a sender’s point of view–you can’t see what’s going on behind the curtain. A different message to the same group from the same sender, based upon content and reputation at the time of sending, might have a totally different placement.
As a sender, you don’t have visibility into any of this activity. You’ll only know whether your email was accepted or not. If an email is accepted, you can’t know whether it hit the “Inbox,” or a “Clutter” or “Promotions” folder where it’s less likely to be opened.
4. Find the right tools to help with inbox delivery
Fortunately, there are tools available to give additional insight into the inbox—SuccessStars’s Deliverability team uses Inbox Monster, which provides reasonably accurate representations of the inbox.
For customers enrolled in SuccessStars’s Enhanced Deliverability Services, we tailor a 250ok list to get an idea of the inbox landscape and to provide guidance on improvements. Other tools include Glock Apps and Return Path, to name a few. But all of these apps come with a hefty caveat: their information is an educated guess, and not guaranteed to be accurate.
5. Optimize and test for mobile
Roughly half of all emails are opened on mobile. Making sure a send is renderable on both computer and mobile is a necessity. Not only that, but many inboxes are configured completely differently on mobile devices compared to desktop. Often, ISPs will route an email directly to spam if it isn’t rendered properly on mobile. Avoid poor performance on mobile devices by using your marketing automation platform’s mobile preview feature to check how your email looks and reads on mobile devices.
6. Sender reputation and email marketing deliverability
When you have a good sender’s reputation, your messages are more likely to hit the inbox. Likewise, a bad reputation will make emails bounce or hit the SPAM folder at a higher rate. Each ISP and filtering company puts different weight on different factors to determine a sender’s reputation.
Reputations can often be found on the postmaster page of the major ISPs. For instance, Google’s postmaster site rates domains on a 4-tier scale: bad, low, medium, high. Other ISPs have different scales and different reasons for affecting reputation.
A good reputation is paramount to a sender, as it can help compensate for any deliverability issues that arise. It also leads to a higher ROI for emails. Good reputation is based on hard work, adherence to best practices, and versatility in a changing landscape. Data quality will have the largest impact on your reputation, followed by maintaining an engaged audience.
Sender Reputation Factors
How they impact you, and whether you can see them
| Visible to Sender/Negative Impact | Visible to Sender/Positive Impact |
| – Spam complaint (at most major providers) – Hard bounce – Soft bounce (from reputation) – Repeated emails to unengaged recipient – Unauthenticated sends – Unformatted/unrenderable content – Hidden links – Bad or blocklisted links – Unsecured links | – Opens – Clicks – Forwards – Replies – Authenticated sends – Double opt-in confirmation |
| Hidden from Sender/Negative Impact | Hidden from Sender/Positive Impact |
| – Sending to a spam trap – Deleted messages – Ignored messages – Email views less than 1 second – User reports as abusive or phishing – Spammy content – User hitting the “This is spam” button (Gmail and most B2B domains) | – Email views greater than 1 second – User creates folder for email – Email promoted to better folder (e.g., Promotions to Inbox) – Moving a message from SPAM – Adding sender to address book – Starring/marking as important |
7. Fixing your bad email sender reputation
Repairing a reputation requires tight control of all email sends and more granular oversight. This is your chance to convince the ISP that you’re following best practices, and that your messages are useful for your audience. Keep these tips in mind if you find yourself with a damaged reputation in need of repair.
- Use only the very best data. Maybe this means that pile of leads from the trade show you just attended has to wait. But it’s better to wait until the repair is complete and your reputation is back on track than send to those untested leads right now.
- Shorten your engagement segmentation period by one-third to one-half. Only email those who are actively engaging with your messages. You’ll likely need to sunset many emails during the repair.
- Perform list hygiene. We’ll cover this in detail in Part 2. In short, you’ll need to perform both third-party list hygiene and sunsetting on your unengaged contacts to ensure data integrity.
Once reputation repair is complete, you’ll need to continue to follow best practices to avoid your reputation slipping. ISPs have long memories; with each reputation hit, it becomes a little more difficult to repair.
8. Performing a hard reset of your email program
A hard reset is exactly what it sounds like: the marketer stops sending any emails from the affected domain/IP for a minimum of 30 days. This might seem extreme, and it can be extremely difficult to convince stakeholders at your organization. But desperate times call for desperate measures. (One reason we recommend that marketers maintain separate traffic streams for different types of emails on different domains: this way not all company email activity has to stop in the event of a reset or reputation repair).
Once the sending has been paused for the requisite 30 days, sending can resume with the following strict setup:
- Only send to the most engaged email recipients
- Ramp-up volumes must be observed closely
- Pause immediately if volumes of emails are not accepted
Maintaining a good reputation is absolutely critical to ensuring inbox placement and avoiding the spam folder. While a bad reputation can be repaired, you should always follow best practices, maintain quality data, and keep your audience engaged to prevent damaging your reputation in the first place.
Stay Tuned for Part II
