Specifying content type and HTML special characters

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Is encrypting emails with special characters and symbols a problem for you?

This is a problem that many email developers struggle with, especially when pasting text from a word processor into the email body. Symbols and characters can also cause display problems in emails when you code emails for different languages.

Setting the content type is the most important factor related to how email clients display text with special characters, including non-Latin languages ​​such as those spoken in Asia, as well as Hebrew, Arabic, and Greek. But email developers can also take matters into their own hands when it makes sense.

If you're seeing red X's, question marks in boxes, or random weird characters that shouldn't be in your emails, we'll take a closer look at what's happening and how to fix the problem. Let's start by answering some important questions.

What is character encoding?

Character encoding is the process of writing or encoding specific symbols in HTML so that they appear as intended regardless of the device, web browser, or email client. This is done by assigning a number or code. If your email encoding is not correct, you will see unexpected symbols and empty fields.

A character set (charset=” ” in HTML) contains a specific group of characters. Each of these characters is represented by a section of code that is used as a key to render the character on a screen.

The Unicode UTF-8 encoding is the most popular and reliable way to define special characters and symbols on the web and in email and other forms of electronic communication. You can set up all your email to use the UTF-8 character encoding. We'll look at that later.

First, however, we should mention that there is a way to ensure that all special characters and symbols in your emails appear as intended.

Indestructible HTML email encoding

If you want to be 100% sure that all text in the subject line and body of your emails is correctly rendered, The safest solution is to convert special characters and symbols into their HTML entities.

As you probably already know, almost every symbol and special character has its own entity name and number. When the entity is inserted into the code, it creates the symbol or character.

These entities always start with an ampersand and end with a semicolon. For example, the HTML entity is used for non-breaking spaces. The use of HTML entities for greater-than and less-than symbols (< and >) can be helpful because they could be confused with tags in the code.

Here are some common special characters and their HTML entities:

There are also HTML entities for email encoding that contain symbols from non-Latin languages ​​such as Chinese or Greek. Characters from these languages ​​can also be represented by Unicode. Here are some examples:

Even if you don't have a global email marketing strategy, you never know when you may need to insert a symbol when email encoding special characters.

Of course, if you want to manually convert special characters in an HTML email, you need to find out the HTML entity. Luckily, we have a free tool for that!

Sinch Email on Acid has developed an HTML character converter to make your job a little easier. Just insert your special characters and symbols, click a button, and get the HTML entities you need to convert into the email body.

Try the character converter

What is a content type?

When you take on the task of email encoding, you can also tell browsers and email clients how to interpret different types of characters by setting the content type. Even if you convert individual special characters to HTML entities, it is useful to define the content type of your email.

You set the content type by selecting the appropriate character set. The two most common character sets are UTF-8 and ISO-8859-1. However, in almost all cases you should use UTF-8 as the content type of an email.

Why is UTF-8 the best choice for character encoding in emails?

Although there are many ways to encode characters, UTF-8 has become an international standard due to its comprehensive functionality. UTF-8 can encode more than 1,112,000 different characters. This includes all written languages, mathematical symbols, musical notations, and even the emojis used in email marketing.

The problem with using the ISO-8859-1 character set is that it only takes into account Latin characters and symbols, which excludes many Eastern symbols and glyphs. The following image shows how such characters are not displayed correctly when using ISO-8859-1 compared to UTF-8

The result on the right contains a lot of confusing text representing the ISO-8859-1 interpretation of the symbols. Note, however, that when using the HTML entity, special characters are displayed correctly for both UTF-8 and ISO-8859-1, making this method foolproof.

Where to specify the content type in emails

When you develop a website, you can set the content type or character set in a meta tag with code like the following:

But as you may know, there are some big differences between web and email development. And this is another one of them. Email clients ignore the content type in the meta tagInstead, email clients always refer to which content type is specified in the email header.

The email header contains a number of technical information about the message, including the date, sender name (from:) and recipient (to:), and email authentication information. When an email client sees the UTF-8 character set defined in the header, it knows how to interpret the characters throughout the message.

How to set the content type in email headers

Below is a code snippet of a specific email header that contains the content type set to UTF-8 at the bottom:

Date: Wed, 15 Dec 2021 12:45:55 -0700 To: test@test.com From: testfrom@test.com Subject: UTF-8 Message ID:
X-Priority: 3 X-Mailer: EOAMailer 5.0.0 MIME Version: 1.0 Content Transfer Encoding: 8bit Content Type: text/html; charset=”UTF-8″

Setting the content type and defining a character set is important for the readability and accessibility of your emails. This ensures that a subscriber's reading pattern is not disrupted, whether the subscriber reads the email themselves or uses an email screen reader.

That's why Sinch Email on Acid offers the ability to set or change the content type in the accessibility settings of the Campaign Precheck automated workflow. With one click, the platform ensures that the correct code is added to the email header.

Since email service providers (ESPs) set the content type in the header, our email development becomes even more complex. If necessary, contact your ESP and ask them what content type they set in the header when sending the emails. Once you know the content type, use that value in your HTML meta tag when designing the email.

Otherwise, you can always rely on the safe method of converting special characters and symbols into the corresponding HTML entities.

Email client support for content types

Another reason to use only UTF-8 for email encoding is that it is widely supported by major email clients. Almost every site on the Internet uses UTF-8 for encoding, as do email clients.

We've done tests to see what clients do when the content type is specified in the header and found that Gmail is the only outlier. Regardless of what is specified in the email header, Gmail is the only client that automatically converts your text to UTF-8. This is also true on iOS when users use Gmail on iPhones or iPads.

We noticed an interesting action: the web-based clients convert your text to the content type's character set before displaying it in a web browser. We were able to verify this by looking at what content type they set in their meta tags. As it turns out, most of them use UTF-8.

Is your email encryption working?

If your email marketing campaigns tend to contain text in different languages ​​as well as special characters and symbols, how can you be sure that they are displayed correctly?

The answer? To be sure, you need to run tests and check email previews.

While you could send manual tests to different types of inboxes, devices, and browsers, Email on Acid provides a streamlined way to test your email encoding and a variety of other factors, including deliverability, inbox display, Outlook rendering issues, dark mode emails, and more.

Email on Acid's mission is to simplify the complexity of email marketing. That's why we develop tools like the handy HTML character converter. And that's why email geeks all over the world trust us.

Try the character converter

This post was updated in February 2022. It was also updated in January 2019 and February 2017 and first published in 2011.

Author: The Email on Acid Team

The Email on Acid content team is made up of digital marketers, content creators, and real email geeks. Connect with us on LinkedIn, follow us on Facebook, and tweet us at @EmailonAcid on Twitter for more interesting stuff and great conversations about email marketing.

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