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29 Email Deliverability Tips 2023

Marketers spent a lot of time drafting poignant email copy, designing amazingly branded email templates, and succinct and enticing email subject lines that will get open and click-through rates skyrocketing.

Just before hitting send, have you counted whether your subscribers will get the opportunity to read your email?

Email deliverability is the rate in which your email truly makes it into recipient inboxes. An email deliverability rate can be less when an email bounces or gets automatically filtered into a spam folder.

No matter how legit an email marketer you are, there are many things you do not know about that can obviate your email from ever reaching anybody inbox. With more severe laws and more sophisticated spam filters, it is to your advantage to know everything that can influence your email deliverability.

If steering clear of legal trouble is not sufficient enough to convince you, pressing more ROI out of your email marketing efforts absolutely should. Take a look at the things you must definitely never do in your email marketing if you want your messages to be correctly delivered and the things you can proactively do to improve your rate of email deliverability.

The first step in improving email deliverability quality will be to run a test to see if you are facing any issues. Want to know more about email deliverability test tools, please click here.

29 Ways to Avoid Sending Spam Emails & Improve Your Email Deliverability

What You Should Never Do?

1. Do not Rent or Buy Email Lists

Yes, you can legally purchase and rent lists of people who have agreed to email communications — but it is a bad idea. Not only is it a mean email marketing method that goes against terms of service for your email service provider, but these people do not actually know you — and more likely, they will not even want your emails. In other words, there is a good possibility they will mark you as spam. Let us be honest; high-quality email addresses have never been for sale.

2. Do not Scrape Sites for Email Addresses

Scraping websites for email addresses might seem like a quick way to build a contact list, but it is not good for your business, not to consider illegal in many countries, including the USA, thanks to the CAN-SPAM Act.

3. Do not Email People Who Have Bounced Repeatedly

Hard bounces are the result of a closed, invalid, or non-existent email address, and these emails will never be correctly delivered. Actually, Bounce rates are one of the key factors that many internet service providers (ISPs) use to determine an email sender’s reputation, so facing too many hard bounces can harm them to stop getting your emails in people’s inboxes.

(Email deliverability is covered largely in HubSpot’s free email marketing certification course, so check it out to learn more.)

4. Use All Caps Nowhere in Your Email or it’s Subject Line

Do not shout at people. It is not kind. While using all caps in your subject line may get the recipients’ attention, but apparently not in a good way. Using all caps can actually rub people the wrong way. It is disturbing and can seem as spammy.

In fact, according to research by the Radicati Group, more than 85 percent of respondents like better an all-lowercase subject line to one in all aspects of caps.

Rather than using disruptive tactics like all caps to catch people’s attention, try making your emails personalized, building relevancy, and using delightful and catchy language. (Kindly read this blog post on how to write compelling emails for further tips.)

5. Do not Use Exclamation Points

Another thing that can make the subject line and/or email look spammy and unprofessional? Exclamation points — mainly a whole group of them in a row. And when 69 percent of email recipients report email as spam based entirely on the subject line, you will want to stay away from triggers like this as much as you can.

In addition, when you order punctuation to do a word’s job, it can really weaken your message. The next time you are motivated to use an exclamation point in an email, use this flowchart, “Should I Use an Exclamation Point?”, as a gut check.

6. Do not Use Video, Flash, or JavaScript within Your Email.

By default, many email clients do not allow the facility to view rich media as video or Flash embeds. Rather, use an image of your video player that links to the rich media on a website page.

While for JavaScript and other dynamic scripts, even if a spam filter permits your email through, the majority of email clients will not allow these scripts to function, so bypass using them altogether.

7. Do not Embed Forms in Your Emails

Forms are not supported in email across regular email clients due to safety risks. Rather, place a call-to-action button or a link to a landing page with a form in the body of your email.

(HubSpot customers: Want to learn how to add a call-to-action button to your emails in HubSpot here, and how to produce a form for your landing pages in HubSpot here.)

8. Do not Include Attachments to Your Emails

If you need to send your recipients something like a Word document or a PDF, do not attach the file to the email; contrarily, your email might get blocked by spam filters. Rather, upload the attachment or any file to your website and than link it to the file location in your email while using an effective call-to-action button. This will reduce the chance of being blocked by spam filters and reduce the load time of your email.

(HubSpot’s attachment tools in the email editor automatically produce this for you. Just highlight an image or a bit of text and click the attachment icon than HubSpot will turn that image or text into a link leading to that attachment.)

9. Do not Use Spam Trigger Words

One of the simplest ways to dodge spam filters is by correctly choosing the words you use in your email’s subject line. A great rule of thumb is this: If it sounds like something a car salesman would say, it is apparently a spam trigger word. Think “guarantee,” “free,” no obligation,” and it goes on. (see this list of common spam trigger words.)

Rather than using these trigger words, be interesting, informative, and creative; without providing too much away. Some more helpful ideas for subject lines include:

  • “Hello [name], [question]?”
  • “Did you learn what you were searching for?”
  • “You are never alone.”
  • “Feeling not okay? Like dogs?”

10. Do not Use a Red Font When Drafting Your Emails

The same goes for using invisible text, that is, white font on the head of a white background. These are basic tricks that spammers use, so it is a prompt red flag for spam filters.

In fact, people do not prefer it when marketers use unusual fonts, font colors, and font sizes all in emails. In the same study by the Radicati Group, from the top ten objectionable email trends, four revolves around fonts. Over sixty percent of respondents viewed it unacceptable for email marketers to try different font sizes, different font colors, and irregular fonts. Nearly seventy percent of respondents favor fonts to be one size.

11. Do not Forget to Use Spell-Check

According to that Radicati Group study, eighty percent of all respondents find grammatical and spelling errors the common unacceptable email offense. But spelling errors are not just unprofessional; they are actually a spam trigger.

It is simple for small spelling mistakes to slip by, especially when you are self-editing. Read this post to learn more about the most common grammar and spelling mistakes, so you will never make them again.

12. Do not Jam-Pack Your Email Copy with Keywords

Keyword-stuffing your emails indicates pushing as many keywords into your emails as you can. There is a reason Google provides a lower rank to webpages that are filled with keywords and is because it is not good to user experience. No one desires to read content that is optimized for a robot.

To make it more likely people will open your emails and not mark them as spam, write your emails for people, not robots. Copywriting that makes folks want to take action is both compelling and simple. To make your writing quality more relatable and personable, use colloquial expressions, casual language, and even personal anecdotes.

I love the example from Turnstyle Cycle (from our roundup of 12 great email marketing examples). The copy is beautiful in its simplicity. It is friendly, yet sincere; especially with the given below lines:

“I know you are busy and would hate to see you miss out.”
“Kindly let us know whether we can help you in any way possible.”
“Feel free to give us a call anytime- we want to help:)”

In addition, they provided me with the exact details I needed to know, a reminder of what I would sign up for, and when, the expiration date, and a phone number to reach them. Check it out:

13. Do not Use an Overwhelming Number of Images or Huge Images

Using just one large image as your entire email, or numerous images, in general, leads to ending up in recipients’ spam folders.

You will also need to make your image file sizes as little as possible without suffering their visual integrity to prevent lengthy email load times. (If you are a HubSpot user, the email tool automatically reduces images size in emails so that they can load faster. For non-HubSpot users, good image compression tools include,, and

Not to consider, Microsoft Outlook does not recognize background images, so you may want to avoid those and rather use a background color.

What You Should Do?

14. Keep Your Email Lists Current and Clean

Also, if your list is completely built on valid opt-ins, you are in jeopardy of being marked a “spammer” if you do not practice proper email hygiene. Why? Because of internet service providers (ISPs) base complaint rates on active subscribers, not total subscribers.

Plus, expired email addresses can turn into SPAM traps, indicating that even if you acquired emails in a legit manner, the abandoned addresses that have not engaged in years might have morphed into spam traps. Going even just one spam trap can make deliverability problems.

Expired email addresses might sometime turn into unknown users. If the unknown accounts at a rate higher than five percent, then internet service providers are going to recognize you as someone who has really poor email hygiene. The result? They will make it more difficult for your emails to reach people’s inboxes, and your all sender reputation will surely drop, leading to even more trouble reaching people’s inboxes.

By managing your email lists current and clean, you will reduce the likelihood people will consider your emails as spam. You can easily identify inactive subscribers and expired email addresses with metrics such as clicks, opens, or website activity.

15. See if You can Reengage Inactive Active Subscribers.

“Graymail” refers to email people technically selected in to receive, but do not really want, driving them to become less active or inactive collectively. Although it is not viewed as spam, sending graymail is doubtful because it can damage the deliverability of your email overall. Tipped off by low engagement rates, internet service providers, and inbox providers may deliver email from known-graymail senders direct to recipients’ “junk” folders, so the email technically gets sent (and can even seem to have been delivered), but it is not necessarily seen.

Keep a record of your inactive and rarely active subscribers, and develop re-engagement campaigns for contacts who have stopped engaging with your messages. For instance, you could place limitations such as the length of time considering their last form submission, email click, or website visit, triggering the email when it has been a while since a contact last engaged with you.

In your workflow, you may try sending them an offer or coupon to get them inspired about your company again. Rather, you might ask them for feedback by sending out a prompt survey to see what they will like to see in your emails. (Read this blog post for many more ideas for launching an email re-engagement campaign.)

16. Do use Double Opt-in

Double opt-in meant that after someone subscribes to your email list, you send them a follow-up email with a verification link assuring they really want to receive email communications from you.

Users that have to verify that they want email communications from your company are the ones that will completely read and engage with the emails they get from your business. When you try to use double opt-in, your email lists will be more qualified, and your subscribers much more involved. (HubSpot customers: Want to learn how to lay up double opt-in in HubSpot here.)

17. You Must Ask Your Subscribers to Add You to Their Address Book

Spam filters are more competitive than ever; so much that sometimes, the email people value and want to read end up in their spam boxes.

But many spam filters allow you to whitelist a sender by summing their email address to their email address book. The good part is when subscribers add you to their address book, and spam filters will definitely back off.

18. You Should Include a Clear Unsubscribe Link and a Physical Mailing Address in Your Email Footer

Permitting people to unsubscribe is essential for list hygiene because anyone receiving your emails should actually want to receive them; unless, you are just spamming them. But do you know that it is illegal not to have a way for your recipients to unsubscribe in many countries, including the United States of America, easily?

In your marketing emails, you should include a way for people to unsubscribe from your email list, either by only sending a reply email or just clicking no more than one level deep to reach a page from where they can unsubscribe. Which way you choose is completely up to you, as long as the information is easy to locate and clear.

The most obvious place for these unsubscribes CTAs is in the footer of your email, so users know to look for it there, which makes for a better user experience. Here is an example, from HubSpot’s emails:

Plus, to unsubscribe links, include a link to update subscriber preferences, which you can also see in the example above. This way, recipients can unsubscribe from just one type of email rather than all of them.

19. Honor Your Unsubscribes List and Remove them from Your Mailing List

If anyone unsubscribes, they come off your email list. It is the law. Check out this list of effective unsubscribers pages to obtain the unsubscribe process a little more delightful for recipients.

This is where email marketing software that combines seamlessly with your CRM comes in handy; because any unsubscribes are quickly processed and recorded in both the contact record and in the email software. (But if you are removing unsubscribed addresses from your list manually, make it a top priority to process that request.)

20. Use a Familiar Sender Name

Because individuals are so inundated with SPAM, they hesitate to open an email from unknown senders. Make sure recipients can identify you in your sender by using your trademark or brand name.

Better yet, send the email from an individual. Recipients are typically likely to trust a personalized sender name and email address than a universal one.

21. Include Your Recipient name in the “To:” Field.

This how, spam filters know that you do, certainly, know your recipient. In addition, personalizing your emails around your contacts can also be important to their engagement with your content.

22. Offer Recipient both an HTML and a Plain Text Version of Your Emails

Plain text emails are just emails void of any formatting, while HTML (HyperText Markup Language) emails use formatting that lets you design more beautiful emails with beautiful visual components. By giving both an HTML version and plain text of a single email, you are not only showing your legitimacy to ISPs, but you are also making your emails more reader-friendly.

Most email marketing tools will let you simply create plain-text versions within their email editor, so take those ten extra minutes to optimize and create the plain-text version of your email.

Also, positively make sure the HTML version is well-coded: If there are defective tags in your HTML, the email users and provider might mark it as spam.

23. Authorize People to View Your Email in a Web Browser

After every step is taken to guarantee proper email design, an email client can still present an email poorly. Include a link in every email to see the email as a web page. (HubSpot customers: Learn how to do this quite easily in HubSpot here.)

24. Include alt text in Your Email Images

Most email clients block images by default. This implies that when someone opens your email, the images will not load except they click a button to show them or modify their default settings — adding alt text to your images benefits recipients to understand your message even if they can not see the images.

This is particularly not good if you utilize an image as a Call-to-Action. Without Alt text, a “turned off” then will look like this:

25. Keep Your Emails Short and Sweet

Too much copying is another red flag for spam filters. Not only that, but people usually like brief emails better. Everybody is busy, and their inbox is already full, so why make things worse?

One of the most reliable ways to keep things short is to write like a human. Try to write your email like you are talking to someone in real life makes it feel much more convenient and relevant.

If you do have to write a longer email, then split it up into many paragraphs. Composing the email and giving visual breaks with a clear introduction, middle, and conclusion will make it quite easier for your reader.

26. Test your Emails before Sending them

There are many email clients out there that email marketers need to consider when creating emails. Other then that, we have to consider mobile users, as well; after all, fifty-three percent of people read email on their mobile gadgets.

It seems that each of these clients displays emails quite differently. While it might be time-consuming to test out your emails for all email clients, you will want to try them for the ones your viewers use the most. By Litmus’ research of 1.06 billion emails 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 allows you to go ahead and preview what your email looks like in various email devices and clients that are quite famous with your audience.

You must also send out a test version of your email before you send out the real deal to ensure it is running properly.

27. Get an Email Sender Accreditation from the Third Party

Sender accreditation is a third-party process of checking email senders and requiring them to track certain usage guidelines. In return, you will be listed in a trusted listing that internet service providers reference to allow a few emails to bypass email filters.

28. Monitor the Reputation of Your Sender IP Addresses

Your emails’ deliverability depends mostly on your IP address’ reputation. If you are sending an email from an IP address with a bad reputation, your emails are far less likely to be favorably delivered to senders inboxes. lets you monitor whether or not you are a blacklisted sender, something many unlucky email marketers are not even aware of.

29. Always Stay up-to-date on Change in Emails Sending Laws, ISP Behavior, and Spam Filter Technology

Email marketing is continually evolving, and staying in the know helps ensure you are always following best practices and the law. Responsible and legit email marketers make a point of regularly reading up on email sending laws, internet service provider behavior, and spam filter technology.

If you are looking for more information, check-in with your company’s legal department to ensure you are staying in the limits of the law. Need to learn about email deliverability? Watch class six in our HubSpot Academy Email Marketing Certification course taught by HubSpot’s Post Master, Tom Monaghan.

Email Deliverability Test Tools

If your email does not offer enough deliverability analytics, we recommend using some other tools that can assist you test for delivery issues before your message goes out to your mailing list.

The Following are three free tools that you can use:

Every time anyone visits, they will see a treehouse with an auto-generated email address listed on it that shifts every time you visit the site. You can easily send your email to the address listed, then click “Check Your Score.” Mail-Tester will then provide you a free email deliverability score establish on the email that was sent to the unique email address.

The software will examine the text in the message, your mail server, and IP to determine if there are any deliverability issues. Free users can access the report for 7days. You can also easily subscribe to unlimited email tests and reports that last for 30 days.

Spamcheck is an easy and free tool that enables you to paste a plain text message into a text box and inspect it for any language that may trigger spam filtering.

After placing the clicking and text “Check your score,” the software will give you a score out of ten based on what is included and not included in the email body. For a bad email, it may look something like this:

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