DELIVTERMS: Inbox Placement (Delivery versus Deliverability)

It's time to define another deliverability term here on Spam Resource! And this time around, as part of the DELIVTERMS series (where I define those confusing email technology terms and acronyms), I'm going to talk about Inbox Placement.

What is Inbox Placement?

Inbox Placement refers to delivering email messages successfully to the inbox, landing your email messages directly in front of users when they open their email client.

• If your messages are getting delivered to the inbox reliably, you've got good Inbox Placement.
• If your messages are getting delivered to the spam folder, or not delivered at all due to bouncing and blocking, then you're not getting good Inbox Placement.

Inbox Placement is often used as a measurement. If you know that your email campaign was delivered successfully to 100% of inboxes, and not delivered to the spam folder at all, then it would be accurate to say that your email campaign had 100% Inbox Placement.

If your sender reputation is poor because of low engagement, lack of permission, misconfigured email authentication or other factors, and all mail is going to the spam folder, it would be accurate to say that your email campaign had 0% Inbox Placement.

If your email campaign send resulted in spam folder placement at Gmail, but inbox elsewhere, and if Gmail made up 60% of your subscriber list, then it would be accurate to say that your email campaign had 40% inbox placement.

Delivery versus Deliverability

Inbox Placement is the key difference between Delivery and Deliverability. Email sending platforms like email service providers (ESPs) and newsletter tools tell you if email messages were delivered, by noting that their sending mail server (MTA) was able to hand the email message off to the receiving mailbox provider's mail server (MTA). You might assume that this means that, because they say the message was delivered, that it was delivered to the recipient's inbox. But that's not always the case!

An email message may not always be delivered to a recipient's inbox. Sometimes, it is delivered to the spam folder (aka junk folder or bulk folder), where it may not be noticed by the recipient. If the mailbox provider believes you to be a spammer or believes your message(s) to be spam or otherwise unwanted, your chances of getting mail delivered reliably to the inbox is very low.

Marketers who send wanted, engaging mail ("good senders"), tend to have their email messages delivered to the inbox. Those who send unwanted mail with low engagement ("bad senders") are far more likely to see that mail delivered to the spam folder (or rejected).

ESPs don't report any of this 'which folder did it go to' information to you. They note only hand-off (delivery) or rejection, not the final folder disposition of the message. Meaning that 100% delivery could equate to 0% Inbox Placement, 30% Inbox Placement, or 100% Inbox Placement.

How to Measure Inbox Placement

How do you know if you're getting solid Inbox Placement? There are multiple third party tools available that help you measure this. The Inbox Monster Inbox Signals Platform, Everest from Validity, and GlockApps Spam Testing are perhaps the most well known of these tools. While they have varying features and functionality, at their core, 'inbox testing' tools like these utilize 'seedlist testing' to provide data showing Inbox Placement results.

The core of seedlist testing works very simply, like this:

1. The testing provider gives you a list of addresses.
2. You include this list of addresses in your subscriber list (or perhaps you load it into its own list).
3. You send to the list periodically.
4. After sending, the testing provider retrieves every copy of the message from every mailbox they have access to in this list.
5. The testing provider generates reporting for you that shows you the disposition of each message sent, in each mailbox, at each provider.

For each address they provide you, that you then send your message or campaign to, they'll report back disposition information that shows:

• The message has been delivered to the inbox,
• The message has been delivered to the spam folder, or
• The message was not found/was not received.

There are add-on features and functionality beyond this; including showing what tab or category a mailbox provider associated with a given message; what blocklists (domain or IP) may have triggered based on message content or infrastructure, what authentication results passed or failed, as well as potentially performing many other tests.

You might look at a seedlist and see an address such as 'meatballmurray2011@outlook.com" and wonder who Meatball Murray is and why this test platform provider would have access to his or her mailbox. Truth be told, the testing provider owns this mailbox. It does not belong to a real person. A seedlist is entirely composed of addresses that the test platform owns; as this avoids most privacy and legal concerns associated with accessing a real person's email inbox to allow a sender to determine the disposition of that sender's marketing message.

If you don't have the budget for a third-party testing tool, or don't see the need for it, I recommend creating your own test mailboxes. Make one or two fresh accounts at the big free webmail providers like Gmail, Yahoo, and Outlook.com. Add these addresses to your email sends, and know that now you've got one or more mailboxes you can login to and manually check to determine whether or not email was delivered to the inbox or to the spam folder. It costs you nothing but time and effort; and it's a great way to begin monitoring. And if you find it valuable, and your need more additional mailboxes and/or reporting grows, then consider utilizing a deliverability monitoring service.

Is Seedlist Testing Accurate?

The short answer is: Yes and no! Seedlist testing is very valuable to enable marketers to understand whether or not their messages are actually getting in front of subscribers. But it has limitations that you should be aware of.

Perhaps the primary limitation is that by default, seedlist addresses don't engage with email messages. Gmail's spam filtering, for example, is highly customizable based on user feedback. Users who report your mail as spam, or who drag it back out of the spam folder, may have different results for Inbox Placement compared to seedlist test accounts who never provide feedback. This means that a static seedlist test's Gmail results might not 100% match the results specific to your actual subscribers' inboxes.

Some seedlist test providers have functionality meant to address this, including 'artificial intelligence' rules applied to certain mailboxes that interact with messages based on certain rules, meant to mimic real user actions and real subscriber personas.

Seedlist testing can also result in Inbox Placement percentages that perhaps do not match the real domain or provider breakdown of a sender's subscriber list. If a seedlist test of 100 email addresses contains 10 Gmail addresses, showing spam folder placement, but the other 90 addresses show inbox placement, then test results would be interpreted as 90% Inbox Placement. But if Gmail was more like 60%-70% of the subscriber list for that sender (as would be the case for most common B2C marketing senders), then the actual Inbox Placement percentage would be more like 30%-40%.

Some seedlist test providers have functionality meant to correct for this as well, using domain weighting or mailbox provider weighting, meant to help skew test numbers in a way to make them more accurately reflect a sender's real domain or provider breakdown.

Alternatively, a testing provider that provides test results for mailbox providers that are not in a sender's database can result in warnings of deliverability issues that don't actually matter. If a marketer's list contains no French email addresses, then a seedlist test result that shows spam folder placement at French mailbox provider, while likely an accurate test result, would not actually need investigation or remediation, as it has no actual impact on overall email deliverability results.

What about Open Tracking?

Historically, open tracking (pixel tracking) was a good method to measure (or at least strongly imply) inbox placement versus spam folder placement. A low open rate meant mail was probably not getting delivered to the inbox. A high open rate was a solid sign of inbox delivery.

In this modern age of Apple MPP, image blocking and image prefetching, open tracking is generally inaccurate and often inflated. But if you do see a sudden, large drop of open rates, this could still be indicative of a new issue with spam folder placement.

Inbox Placement: Should you monitor, or not?

While the seedlist testing methodology does have limitations, I do personally think it's valuable. I utilize it myself, and I do generally recommend it to others. Just like with open tracking, many marketing and newsletter senders do find it useful for trending and issue identification, even though it may not always 100% reflect real world results.

Fun Fact: History of Inbox Monitoring (maybe?)

A company called Pivotal Veracity might have been the first to offer inbox placement tracking. I remember using their 'eDelivery Tracker' tool in 2004 or 2005, while working for e-commerce provider Digital River – at the time, the tool came highly recommended by friends at email service provider BlueHornet. I continued to utilize Pivotal Veracity's eDelivery Tracker for years – here's a sample report from 2008.

Learn More

Wow! That explainer went on a bit longer than I had planned, but I hope you enjoyed it! If you'd like to learn more about deliverability terminology, I hope you'll head on over to the DELIVTERMS section here on Spam Resource, with 30+ email deliverability and technology terms and acronyms defined!