After spending countless hours in drafting poignant email copy and crafting succinct and captivating subject lines, you want to be sure that your emails are actually being opened and clicked through by your subscribers.

However, according to Sendgrid’s email deliverability statistics, a whopping 21% of emails never reach the recipients’ mailboxes. These 21% emails aren't even hitting the spam folder - it's worse, they are being outright rejected by the email servers. That’s because many senders don’t follow email deliverability best practices.

As studies have proven multiple times over, email marketing is, hands down, the best way to reach your customers.  But if the recipients never get your emails, you’re wasting time and money, and missing out on leads and revenue.

The only way to solve that is by following best practices for email deliverability so more of your emails reach the inbox.

In this guide, we’re going to outline things you should absolutely never do in your email marketing if you want your emails to be successfully delivered, and the things you can proactively do that’ll help you reach more of your subscribers’ inboxes.

What You Should Never Do

1. Don't buy or rent email lists.

It's never a good idea to rent or purchase lists of email addresses esp. those who haven't agreed to receiving email communications from you. It's only is a dirty email marketing tactic but violates the GDPR law and other privacy laws as well. Purchased email lists are simply not compliant with these privacy laws. Not to mention, these people don't know you or your business and are most likely going to mark your email as spam. And if you want to maintain a high deliverability rate, that's the last thing you'd want.

For the best deliverability, be sure everyone on your subscriber list knew exactly what they were signing up for and try to keep reminding them of this once every couple of emails that you send.

2. Don't send emails to unengaged subscribers

Email engagement also improves your deliverability and inbox placement rates.

Modern spam filters prefer and trust senders with high open and click-through rates and constantly keep track of the engagement rates for each sender. Using this data, ESPs can identify and filter out emails that your recipients aren't opening or clicking. Sending emails to such unengaged subscribers lowers your deliverability rates and your future emails will end up in the junk or spam folder. And by continuing to send email to contacts who don't open or click, you're lowering your overall sender score.

We recommend avoiding sending emails to unengaged contacts completely. If you are sending emails from Gist, in the Recipients tab of your one-off email messages, select the Don't send to unengaged contacts checkbox to automatically exclude contacts who aren't interacting with your marketing emails.

This makes it extremely important to make sure that subscribers are receiving email content they actually want and on an expected schedule established upon signing up for your email list.

3. Don't scrape sites for email addresses.

It may seem like a fast way to build a contact list at first, but scraping websites for email addresses is bad for your business - not to mention illegal in many countries, including Europe & the United States, thanks to the GDPR and CAN-SPAM Act.

The CAN-SPAM Act governs marketing email, aka any email sent by a business trying to promote or sell a product or service.

The rules of CAN-SPAM are:

  • Don’t use false or misleading information
  • Don’t use a deceptive subject line
  • Tell subscribers where you’re located
  • Give subscribers a simple way to opt out of your emails
  • Honor all opt-outs quickly

4. Don't include attachments to your emails.

As we have told many times, offering content upgrades on your blog posts is the most effective and quickest way to grow your email list. And to deliver the lead magnets, you'll need to send your subscribers something like a PDF or a Excel document, but do not attach the file directly to the email. Most spam filters are configured to automatically block emails that have attachments. Instead of sending the document as an attachment, upload the file to your website or to any cloud storage and drop a link to the file in your email using an effective call-to-action.

This'll minimize the chance of being blocked by spam filters and decrease the load time of your email.

5. Don't use spam trigger words.

Sometimes the words you choose are what’s keeping you from reaching your prospect. As the saying goes, “if it sounds too good to be true, it probably is.”

Spam filters have become more advanced in recent years. They won’t automatically send you to spam for saying “limited time” or “get started now” - if you’re using those words responsibly.

Here are a few types of spam words and phrases to use with caution:

  • Words that make exaggerated claims and promises
  • Words that create unnecessary urgency and pressure
  • Words that look like shady, spammy, or unethical behavior
  • Words that are jargon or legalese

This applies most to your email subject line. Words like “free,” “money,” “help” and “reminder” all trigger content-based email spam filters. Especially if you’re not added as a contact in your recipient’s email database.

6. Don't use all caps anywhere in your email or its subject line.

Some people mistakenly believe that using all capital letters in their email or subject line is a great way to get the attention of the recipient. What they fail to realize is that using all caps is a great way to trigger SPAM filters, and even if your message gets through, it’s annoying, makes you look shady, and just isn’t professional.

5. Don't use exclamation points!!!!!

Like emails with all caps, emails with exclamation points is highly likely to be marked as spam. Especially when they’re in the subject line.

6. Don't use an overwhelming number of images, or huge images.

Using one large image as your entire email, or too many images in general, tends to end up in recipients' spam folders.

Note: The common rule of thumb used to be to maintain a 60/40 text-to-image ratio. But recent research from Email on Acid shows that restrictions like this depend on the length of an email.

Their findings:

  • Emails less than 500 characters should contain a supporting image

  • Emails over 500 characters are not significantly impacted by image/text ratio restrictions

You'll also want to make your image file sizes as small as possible without losing their visual integrity to prevent long email load times. (If you're a Gist user, the email product automatically compresses images in emails so they load faster. For non-Gist users, some good image compression tools include,, and

Not to mention, Microsoft Outlook doesn't recognize background images, so you may want to avoid those and use a background color instead.

7. Don't send emails to inactive or unengaged subscribers

"Graymail" refers to email people technically opted in to receive, but don't really want, leading them to become less active or inactive altogether. Although it's not considered spam, sending graymail is problematic because it can hurt the deliverability of your email overall. Tipped off by low engagement rates, ISPs and inbox providers may deliver email from known-graymail senders straight to recipients' "junk" folders -- so the email technically gets sent (and can even appear to have been delivered), but it's not necessarily seen.

What You Should Do

1. Keep your email lists current and clean.

Even if your list is entirely built on valid opt-ins, you are at risk of being branded a "spammer" if you don’t practice proper email hygiene. Why? Because internet service providers (ISPs) base complaint rates on active subscribers, not total subscribers.

Also, expired email addresses can turn into SPAM traps, meaning that even if you acquired emails in a legitimate manner, the abandoned addresses that haven't engaged in years may have morphed into spam traps. Hitting even just one spam trap can cause deliverability problems.

By keeping your email lists current and clean, you'll decrease the likelihood people will flag your emails as spam. You can identify inactive subscribers and expired email addresses with metrics such as opens, clicks, or website activity.

Your goal is not necessarily to have the largest email list but to have the most engaged email list possible. If your email list boasts large numbers of subscribers but your open and click rates are dismal, it won’t turn into more conversions.

2. Do use double opt-in.

Double opt-in means that after someone subscribes to your email list, you send them a follow-up email with a confirmation link ensuring they actually want to receive email communications from you.

Users that have to confirm that they want email communications from your company are the ones that will fully read and engage with the emails they receive from your business. When you use double opt-in, your email lists will be much more qualified and your subscribers much more engaged.

3. Ask your subscribers to add you to their address book.

Spam filters are more aggressive than ever -- so much so that sometimes, the emails people value and want to read still end up in their spam boxes.

But most spam filters allow you to whitelist a sender by adding their email address to their email's address book. When subscribers add you to their address book, spam filters will back off.

4. You must include a clear unsubscribe link and a physical mailing address in your email footer.

Allowing people to unsubscribe is important for list hygiene because anyone receiving your emails should actually want to receive them -- otherwise, you're just spamming them. But did you know that it's illegal to not have a way for your recipients to easily unsubscribe in many countries, including the United States?

The most common place for these unsubscribe CTAs is in the footer of your email, so users tend to know to look for it there -- which makes for a better user experience. Here's an example from one of Gist's emails:

In addition to the unsubscribe link, include a link to update subscriber preferences, which you can also see in the example above. That way, recipients can unsubscribe from just one type of email instead of all of them.

5. Use a familiar sender name.

Because people are so inundated with SPAM, they hesitate to open email from unfamiliar senders. Make sure recipients can recognize you in your sender by using your brand name.

Better yet, send the email from a real person. Recipients are typically more likely to trust a personalized sender name and email address than a generic one. At Gist we found that that emails sent from "Paulina Novicio, Gist" perform better in terms of open and click-through rate than emails sent from just "Gist."

6. Test your emails before sending them.

There are a lot of email clients out there these days that email marketers have to consider when creating emails. On top of that, we have to consider mobile users, too -- after all, 53% of people read email on their mobile devices.

It turns out each of these clients displays emails differently. While it may be time-consuming to test out your emails for all email clients, you'll want to test them for the ones your audience uses the most. According to Litmus' research of 1.06 billion email opens, the top five email clients are:

  • Apple iPhone's Mail app (28% of users)
  • Gmail (16% of users)
  • Apple iPad's Mail app (11% of users)
  • Google Android's Mail app (9% of users)
  • Outlook (9% of users)

If your email marketing tool lets you, go ahead and preview what your email looks like in different email clients and devices that are popular with your audience. (Gist customers: Use our Preview in other inboxes feature to send a test email and see how the design of your email looks in each email client.)

You should also send out a test version of your email before you send out the real deal to ensure it's working properly. (Gistcustomers: Learn how to test your emails here.)

7. Send plain-text emails

Why do people read your emails? It’s not because of the design but rather the value of the content inside your email. With this in mind, we recommend sending plain-text emails.

Not only do they eliminate distracting visuals but they also feel more like an email from a friend than a visual-heavy promotional email.

You can still include imagery in your Gist emails when applicable. However, it’s best to keep imagery to a minimum since images reduce your load times and could mark your emails as potential spam.

8. Monitor your email marketing metrics

Your email marketing efforts won’t be as successful if you aren’t actively measuring the performance of your emails. Email marketing metrics—like open rates, conversion rates, and click rates—are there to help you understand how well your audience is engaging with your emails.

As you monitor the performance of your email campaigns, you can continue to optimize your email sequences over time and create stronger subject lines by sending single email broadcasts.

9. Personalize emails to your subscriber

There’s no denying that we love to hear someone say our name. It helps us feel seen in a world that feels noisy and crowded at times. Personalizing your emails with a custom greeting will help you create a stronger connection with your subscribers.

There are a few ways you can do this in Gist, and it only takes a few seconds. That small time investment can reap big rewards by helping you build trust.

It’s very important that you address your users as actual people, and not some lifeless beings. Opening your email with the typical ‘Hi there’, or ‘Dear Subscriber’, etc., is a bad idea, because that tells them that you are sending the email to many people at once, and that they’re not special in any regard.

Remember that you need to talk to users as a friend, and not as a salesperson. And that is why you need to personalize each message so that it's customized to everyone who gets it. But the challenge is that you’re mailing thousands of customers. Then how can you be personal?

10. Test the email as a recipient

Before you finalize the email, send the email to yourself or to a close associate and view it from the other end as a potential customer. Observe how it makes you feel, and make changes wherever necessary.

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