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Newsletter 101: The Ultimate Guide to Email Deliverability

A simple guide to understanding email deliverability for your newsletter

For anyone with a newsletter, understanding email deliverability is crucial.

To start, let’s define it:

Email deliverability is when an email successfully arrives in a recipient's inbox.

And while we’re at it, let’s define a few other key terms with examples:

Email Service Providers (ESPs) send email on your behalf (e.g., beehiiv, Mailchimp, Sendgrid, etc.)

Internet Service Providers (ISPs) are the ones who provide you with an email address (e.g., Gmail, AOL, Verizon, Outlook, etc.)

The goal of ESPs is to successfully deliver emails to your readers on your behalf and report insights and metrics. The goal of ISPs is to use spam-blocking measures to help sort through incoming emails and identify the spam to keep their customers happy.

If Gmail didn’t do an incredible job of sorting spammy emails into your Junk folder, your inbox would overflow with spam, and you’d look to use another ISP for email.

Simple enough, but from the moment you press send until it arrives in your readers’ inboxes, it can seem like a total black box as to what’s happening behind the scenes. And the truth is, it is a black box, intentionally.

ISPs look at thousands of different variables for any given email to accurately determine if it should be classified as spam. If they made these parameters publicly available, it’d be too easy for nefarious senders to game the system.

So what can you do to optimize your newsletter’s email deliverability? In this blog post, we’ll answer these questions:

  • How do I avoid the spam folder?

  • How do I prevent Gmail from classifying my mail in promotions?

  • Why do some readers claim they aren’t receiving my mail?

  • What does beehiiv do to ensure the best possible deliverability?

How do I avoid the spam folder?

While this isn’t an exhaustive list (as mentioned above, there are thousands of potential variables, and they vary from ISP to ISP and person to person), here are some primary factors ISPs analyze in real-time in determining where to deliver your email:

  • Email content — this includes the subject line, pretext, body content, and more. Content is scanned for keywords and phrases that ISPs consider spammy. Examples of this can be large dollar amounts or “porn.”

  • IP reputation — each email is sent from a specific IP address, of which, has its own unique reputation from previous email campaigns.

  • Domain reputation — this is the email address you’re sending the campaigns from (e.g. @beehiiv.com for us), and it also has a unique reputation from previous email campaigns

  • Images — images previously flagged as spammy, or emails that contain too many images with too little text can often trigger spam filters

  • URL blocklists — if a URL is placed on a blocklist (i.e. some phishing or scamming site), and your email contains that URL, your mail will likely be flagged as spam

  • Recipient preferences — each recipient has their own additional preferences and spam filters to further make their filters more strict (or vice versa)

  • Individual spam treatment — if a recipient has previously marked one of your emails as spam, it’s likely future emails will also be marked as spam for that reader

There are a few key things to note here...

First, every inbox and every recipient is different. An email that’s classified as spam in Yahoo may not be classified as spam in AOL. Similarly, a reader who uses AOL may receive your email in their primary inbox, while another reader who also uses AOL may receive that same email in their spam folder. This is due to the different preferences, previous email history, settings, and more. This makes deliverability pretty frustrating for most senders.

Second, some of these factors vary from email to email. For example, you may have an incredible IP and domain reputation…but if one particular email contains spammy content or a blocklisted URL, it’s possible that email may end up in junk. And again, it varies by ISP and recipient, so it’s possible to see regular fluctuations in your engagement.

Lastly, the most important thing you can do is build a strong IP and domain reputation. These are essentially a report card of how your campaigns have been performing historically. To understand this you have to understand both the positive and negative engagement metrics ISPs look for. These metrics are aggregated at both an IP and domain level.

Positive engagement metrics

🔥 email open

🔥🔥 email click

🔥🔥🔥 email forward

🔥🔥🔥 email reply

🔥🔥🔥 move email to primary inbox

Negative engagement metrics

🧊 delete before opening

🧊🧊🧊🧊 mark as spam

Both positive and negative engagement metrics are weighted differently. While this isn’t an exact science, we used emojis to signify a slight weighted difference in importance. The reasoning behind this is fairly simple. As an example, let's consider two different senders:

Sender A average metrics

5% open rate

1% click-through rate

1% spam rate

Sender B average metrics

35% open rate

6% click-through rate

0.05% spam rate

Assuming all else is equal (email content, images, URLs, etc.), ISPs will favor placing mail from Sender B in recipients’ primary inboxes and be much more cautious about Sender A. It’s also worth noting that these reputations are built up over time. If you have a single campaign with incredible engagement, that doesn’t mean your next email will automatically be placed in the primary inbox. It takes months (and years) to build up a reputation with ISPs to show that the domain and IP you’re using to send email is trustworthy and the mail you’re sending is engaging.

So long story short, what are the most important things to prioritize to avoid the spam folder?

  1. Acquire quality subscribers who are engaged and knowingly opted-in to your email list

  2. Send engaging newsletters that people are eager to both open and click

  3. Avoid sending too frequently or sending to non-consensual subscribers… either one could lead to spam complaints

  4. Churn your un-engaged subscribers over time to ensure a pristine and engaged list (i.e. remove readers who haven’t opened in a while)

  5. Optimize for clicks and replies when possible

How do I prevent Gmail from classifying my mail in promotions?

The answer is actually simple (and frustrating) because there is no silver bullet. It requires following the recommendations stated above over a long period of time, and proving to Gmail you deserve to be categorized as an update.

It’s also very possible that your emails, by nature, are more of a promotional type of email… thus, you may be getting classified correctly.

Why do people care about the tab into which Gmail categorizes their mail?

It’s because some users don’t have an updates tab enabled. So mail that is categorized as an update is slotted into the primary inbox. Alternatively, the promotions tab can be stuffed with e-commerce sales and mailing lists that make it harder to find your mail.

At Morning Brew, we spent years being classified as promotions prior to being moved over to updates. On beehiiv, we’ve seen tons of users initially classified as promotions but move over to updates in just a few weeks.

The truth is—it all depends.

But you just need to control what you can by following the five steps above AND by configuring a custom sending domain. That means all of your emails sends from @yourdomain.com, and that reputation is yours irrespective of what ESP you use. The sooner you start using a custom domain, the sooner you can build a stronger domain reputation over time.

Why do some readers claim they aren’t receiving my mail?

First—double-check that they are actively subscribed to your newsletter. It’s possible they accidentally unsubscribed, so it’s nice to cross that option off the list before throwing stuff at the wall.

Second—ask if their email ended up in spam. As frustrating as it is, it’s very possible your email landed in their junk folder. It’s always good to at least cross that off the list as well.

Third—if they’re using a corporate email, their corporation may have stricter spam filters and block the mail. You can reach out to our support to confirm that that was the issue. If that is the case, the recipient's firewall administrator will need to change the firewall rules for them to be able to receive your mail on a regular basis.

For recipients having issues with their firewall blocking mail, we recommend sending the following email to an affected reader:

A sample email you can send to readers

Hey, it's likely that your employer and/or network has a strict firewall in place blocking our newsletter. You just need to submit a quick request to IT to safelist the following domains, and the issue should resolve itself:

  • *beehiiv.com

  • *beehiiv.net

  • *yourdomain.com

This should be a pretty straightforward request, and IT should know what to do with that information.

What does beehiiv do to ensure the best possible deliverability?

We take email deliverability incredibly seriously because at the end of the day if your emails aren’t reaching your readers, what’s the point of everything else?

The primary things we do to ensure optimal email deliverability:

  • Allow configuration of custom sending domains so you own your domain reputation

  • Custom IP infrastructure to ensure the highest quality IP reputation per send

  • Integrated 3rd party email validation to ensure legitimate emails on your list

  • Strict onboarding verification to ensure quality senders on the platform

  • Custom guardrails to flag prevent and remove poor senders on the platform

  • Cross-referenced suppression lists to avoid poor sending practices

  • Built-in Gmail clipping warning

  • Best-in-class deliverability support team

Want to take your newsletter to the next level? Trust the platform built by people who have a proven track record...

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