The Ultimate Email Deliverability Guide: 9 Ways to Get More of Your Emails into Your Subscriber’s Inbox

A Guide to Email Deliverability

Can I dazzle you with some statistics?

Twitter sees an average of 6,000 tweets every second. (That’s 500 million tweets per day.)

Around 1.13 billion people post or consume content on Facebook every day.

In the U.S. alone, a 2013 study found that the average smartphone user sent 880 texts and received 898 per month.

These are impressive numbers, for sure.

But they all pale in comparison to the roughly 453 billion emails sent worldwide each day.

That’s an important statistic you may already know if you’re an email marketer. But here’s another important statistic that you might not know…

Nearly 86% of all that email sent every day is considered spam—unsolicited or unwanted email.

Because of this rampant abuse, mailbox providers have gone to extremes to protect their customers’ inboxes. In 2016, Return Path reported that 24% of emails sent by brands never reached their destination—and that percentage was rising.

The bar keeps getting higher.

If you want to make the most of your email marketing, you need to make sure your emails are getting to your subscribers’ inboxes.

And that’s why we’ve put together this comprehensive guide to email deliverability.

A note before we get started: if you haven’t yet tried Drip for your email marketing, you should know that it puts you ahead of the deliverability game. I’ll talk a little bit more about that in the course of this guide, but if you’d like, you can go ahead and set up your Drip account here:

Join Drip + Boost Your Email Deliverability

Let’s dive in.

Sender Reputation: The Secret to Sky High Deliverability Rates

Email service providers all tout their spectacular deliverability.

But here’s the truth.

When it comes to email deliverability, there’s really only one thing that will move the needle and ensure you get into your subscribers’ inboxes on a regular basis.

I’m talking about your reputation.

The truth is, nothing will boost your deliverability if you have a bad sender reputation.

The good news is it’s easy to establish and maintain a stellar sender reputation (and keep your deliverability rates high) if you understand the basics.

How Focusing on Subscriber Engagement Will Give You an Edge Over Your Competition

Today’s mailbox providers (like Gmail, Yahoo, and Outlook) all calculate reputation scores for your domain.

And that reputation score rises or falls based on your level of subscriber engagement. The more your list engages with you, the better your reputation!

While it’s important to note that mailbox providers all have their own criteria and algorithms for measuring engagement, there are certain common indicators—both positive and negative—that they look at.

For example, your sender reputation goes up when subscribers:

  • Open an email
  • Reply to an email
  • Forward an email
  • Mark an email as “not spam”
  • Move an email to a folder
  • Whitelist or add your sender domain to their address book

Negative indicators, on the other hand, include actions like deleting an email without opening it or marking your message as spam.

The challenge, however, arises from the fact that most of these actions aren’t apparent to the email sender. You won’t know whether a message was forwarded or marked as “not spam” or deleted without being opened or moved to a different folder.

This is why your processes and practices are so critical in building your reputation.

So what processes should you implement to maintain a clean reputation?

Maintain the Right Email Processes and Practices for Maximum Engagement and Deliverability

Ten years ago, email success was about having the biggest list possible. Today your sender reputation depends on your having a high-quality list of engaged subscribers.

Here’s a series of processes and checks you want to implement to ensure your reputation is stellar and your email deliverability is off the charts.

1. Build a Clean List with Double Opt-Ins

When you’re building your list, go the extra mile and use a double opt-in.

While the extra step may seem annoying, it can actually add a level of confidence that you’re a legitimate sender. (It also gives you an important opportunity to interact with them early in your relationship as I’ll show you in just a second.)

This gives new subscribers an initial window to show that they’re engaged; if there are no signs of life after the time period you select, they’ll be cut from your list. It gives you the best of both worlds: maximum sign-ups and minimum “junk” emails on your list.

Super Pro Tip: With Drip, you can also choose to automatically resend confirmation emails to folks who don’t click your confirmation link after several days. This is a one-click option, available in every Drip account.

2. Clean Your List on a Regular Basis

In some email providers, you need to scan your list for duplicate addresses, known previous bounces, bad address structures, nonsense or profane entries, obvious misspellings, and potentially harvested addresses (such as info@, sales@,

When you find addresses like these, suppress them right away.

Beginning with a clean, qualified list is the easiest way to boost your deliverability.

And finally…

Never, ever mail to a purchased list.

Purchased lists are usually full of scraped or harvested email address that can include large numbers of spam traps. (The folks at Word to the Wise offer a detailed explanation of spam traps here.) More importantly, these lists are names of people who didn’t opt in to hear from you.

In any major email platform, purchasing lists (or “cold emailing”) is prohibited.

It bears repeating: never—NEVER—mail to a purchased list.

Note: Here at Drip, before any new client can start mailing, we do a realtime scan of their email list and validate every email address, removing any known dead, undeliverable, or suppressed addresses.

Yes, it’s an extra step before your first send. But it means you’re joining an exclusive, pre-vetted group of email marketers—the kind that email providers trust. Everyone’s deliverability is higher when your email platform takes precautions like these.

3. Make Your Unsubscribes Work for You

One of the mandates of the CAN-SPAM Act of 2003 is that opt-out links must be clearly displayed in every email. If you don’t have one, you’re technically in violation of the law.

Some marketers may try to obscure their link hoping to dissuade their subscribers from unsubscribing. That’s a bad idea.

You can offer them the option to modify their subscriptions in case they only want to opt out of a campaign (a feature we offer in Drip).

On the other hand, if someone on your list wants out completely, you should let them go.


You should also use the opportunity to gather as much information as you can.

Unsubscribe pages can also be a great way to collect feedback on your mailing habits. Many marketers will offer a survey when someone unsubscribes asking why they’re leaving. This kind of information can be invaluable to offering relevant, valuable content and keeping your deliverability rate high.

4. Be Aware of Bounced Addresses

Sometimes people enter bogus email addresses just to get a cool download. Sometimes they may just make a typo.

Either way, bad email addresses can cause your marketing emails to bounce, and you need to be aware of them.

A “bounce” is simply an undelivered email. They come in two flavors—hard bounces and soft bounces.

Hard bounces occur when emails are sent to invalid addresses—one where the domain may not exist or the recipient may be unknown.

Soft bounces, on the other hand, occur when an email reaches your recipient’s email server but is not immediately delivered. This can happen for any number of reasons, such as a full inbox or a server problem. Usually a soft bounce will be delivered on a subsequent attempt.

Most ESPs will have a means of handling bounces.

For example, here at Drip we immediately suppress hard bounces. For soft bounces, we’ll monitor the address. If the next three delivery attempts bounce, we automatically mark it as undeliverable and suppress it.

What’s important to understand here is that all ESPs handle bounced addresses differently. Some may only suppress bounces for a certain period of time. Others may not suppress bounces at all.

Be sure you know how your email provider handles bounces.

An occasional bounce won’t kill your reputation. However, repeated attempts to mail them will.

5. Prune Your List

Pruning your list means proactively unsubscribing email addresses that are not regularly engaging with your content. It’s a painful but necessary exercise. In fact, it’s probably one of the most important things you can do.


Once upon a time, spammers attempted to game deliverability checks by loading their lists with inactive addresses—addresses that wouldn’t bounce, but also would never click a spam complaint.

To counter this tactic, mailbox providers began measuring engagement against active email addresses.

Let’s say you’re mailing to a total list of 10,000 names—but 9,000 of them are inactive. And suppose you get 100 spam complaints. You might think your complaint rate is a negligible 1%. The mailbox provider, however, is seeing a complaint rate of 10%. That’s a big difference.

Use a re-engagement campaign for inactive email addresses that haven’t opened, say, your last 15 emails.

If they don’t respond, prune ‘em. (Drip makes this easy!)

While doing this can feel painful, it will benefit your reputation and deliverability far more in the long run.

6. Monitor and Analyze Your Spam Complaints

Spam complaints are a fact of email marketing life.

Sometimes when a subscriber no longer wants to receive your content they’ll click the spam “Report Spam” button instead of unsubscribing.

Don’t take it personally.

Like with bounced addresses, your ESP should have a means to suppress addresses that issue a complaint so there shouldn’t be much for you to do here.


Spam complaints can be a valuable source of information and you should take time regularly to analyze it. Consider the content of any campaigns that generate a high number of complaints, the segment it was sent to, times they were sent etc.

In Drip you can call up an events report that will show you the trend of spam complaints you get over time. You can drill down on subscribers in the list to see what might have caused them to click their spam button.

Identifying the causes of complaints and making appropriate adjustments is a huge way to increase deliverability.

7. Establish and Maintain a Regular Mailing Schedule

Size matters. So does frequency.

You want to be consistent where both are concerned.

Wild fluctuations in the size and frequency of your email broadcasts can attract the attention of blacklists and other email IP monitoring entities.

For example, let’s say you mail to a list size of 500 one week, don’t mail for two weeks and then suddenly start blasting to 10,000 addresses at a time. That will definitely raise some eyebrows.

On the other hand, consistency in your email schedule will encourage engagement and help build your reputation.

If your list expects to hear from you on Thursdays, make sure you mail on Thursdays. If they expect to hear from you twice a week, mail them twice a week.

Be consistent. It builds trust and credibility—both with your subscribers and mailbox providers.

8. Create and Use Clean, Consistent Email Templates

Just as important as the content that goes into your email is the technical stuff. Here’s a quick rundown of what you want to check in every email.

  • The CAN-SPAM Act of 2003 stipulates that all commercial email must contain two pieces of information: your physical mailing address and a clear way to opt out of your list. Make sure they’re included in all your emails. (Note: Most email service providers, Drip included, won’t let you mail unless you’ve entered that information.)
  • Don’t try to put interactive content like JavaScript or embedded forms in your emails. Most email clients won’t even enable this kind of functionality. And the security risks these scripts present will usually get you sent straight to the junk folder.
  • Don’t send attachments. Instead, link to the file you want to send. You can upload it to your website, a hosting service, or simply a public folder within Dropbox or Google Docs.
  • Make sure your HTML code is clean. Spammers often try an end run around spam filters by placing HTML tags throughout their emails to hide any malicious code. A messy template is a suspect template and they’ll usually head for the spam folder.
  • Be visible and branded. Using a clear, consistent “From” address will help increase open rates.
  • Watch your language, too! While it’s no longer the main way they determine deliverability, mailbox providers’ spam filters still monitor subject lines and email content. Keep an eye on your personal spam folder—if your email sounds like anything that’s landing there, adjust before sending.
  • Keep the ALL CAPS and THE EXCLAMATION POINTS!!!!! to a minimum. They’re surefire triggers for spam filters.
  • Finally, always be sure to proofread your emails. Spammers are known for frequent misspellings and poor grammar within emails.

9. Welcome Your Subscribers with Open Arms (and Some Instructions)

Your subscribers will never be happier to hear from you than when they first sign up.

So once a subscriber confirms they want to be on your list, your onboarding process should include immediately sending a welcome message. (Or better yet, send a welcome series!)

Welcome emails are the easiest way to get a great relationship off the ground and start generating engagement. Studies have shown that welcome emails have open rates four times higher and clickthrough rates five times higher than regular broadcast emails. So use that to your advantage.

A good welcome email should ideally get your subscriber to take an action or click a link. One of the best reputation-building actions you can get them to take is to whitelist your domain or add you to their address book to ensure they don’t miss any of your emails.

Welcome emails are a layup opportunity to build your sender reputation. Don’t skip them.

Skyrocket Your Sender Reputation and Email Deliverability with Drip

These are the key things you can do to build a stellar sender reputation—the most important consideration in email deliverability today.

So how do your email marketing processes stack up?

If you’re not sending your marketing emails from a platform designed to support all of the above deliverability-boosting practices, the best thing to do right now is to find one.

Of course, we’d recommend you give Drip a close look while you’re looking. (It’s free for up to 100 contacts if you’d like to test it out.)

Join Drip + Boost Your Email Deliverability

From there, there’s so much more you can do to ensure your subscribers are receiving the most relevant and persuasive content for them at that moment: behavior-triggered emails, automation workflows that automatically segment contacts into the right buckets, smart links that let subscribers choose their own adventure.

But it all starts with deliverability. Go nail this down—and you’ll see better email stats month after month.

What questions or concerns do you have when it comes to email deliverability? Let us know in the comments below.