Best Practices for Plain Text vs. HTML Emails: A Comprehensive Guide With Case Study

Introduction

Email marketing remains one of the most effective ways for businesses to communicate with customers, generate leads, promote products, and build long-term relationships. However, creating an effective email involves more than writing a compelling subject line and choosing the right audience. Senders must also decide how their messages should be formatted. Two of the most common options are plain text emails and HTML emails.

Plain text emails contain readable text without advanced visual formatting, while HTML emails can include colors, images, headings, buttons, columns, and other design elements. Each format offers different advantages, and choosing the right one can influence readability, accessibility, engagement, and the recipient’s overall experience.

Some businesses assume that HTML emails are always more effective because they look professional. Others believe that plain text emails are more trustworthy because they resemble personal correspondence. In reality, neither format is universally superior. The best choice depends on the purpose of the email, the audience, the devices recipients use, and the type of experience the sender wants to create.

This article explores the differences between plain text and HTML emails, explains best practices for each format, discusses deliverability considerations, and presents a hypothetical case study showing how a business can use both formats effectively.

1. Understanding Plain Text Emails

Plain text emails consist primarily of standard characters, words, and basic line breaks. They do not rely on HTML formatting to display colors, images, complex layouts, or styled buttons.

For example, a plain text email might look like this:

Subject: Your Weekly Marketing Tips

Hello Sarah,

Here are three ideas to improve your email campaigns this week:

1. Write clear subject lines.
2. Send relevant content to interested subscribers.
3. Review your bounce and complaint rates regularly.

You can read more in our latest guide:
https://example.com/email-guide

Best regards,
The Marketing Team

This format is straightforward and easy to read. It works across a wide range of email clients and is particularly suitable for personal communication, brief announcements, simple newsletters, and text-focused updates.

Advantages of plain text emails

Simplicity: Plain text messages are generally easy to create and maintain.

Readability: Without complex layouts, recipients can focus on the message itself.

Compatibility: Plain text works well across many devices and email applications.

Accessibility: Text-based messages can be easier to navigate with assistive technologies when written with clear structure and descriptive links.

Personal communication: Plain text can feel conversational and direct, particularly for one-to-one business correspondence.

Limitations of plain text emails

Plain text has fewer visual presentation options. Senders cannot create richly styled buttons, product galleries, branded banners, or complex layouts using plain text alone.

Links may also appear as long URLs, which can make messages less visually tidy. In addition, long messages can become difficult to scan if they lack clear headings, spacing, and concise paragraphs.

Plain text is therefore most useful when clarity and direct communication matter more than elaborate design.

2. Understanding HTML Emails

HTML emails use HyperText Markup Language to structure and style email content. They can include headings, formatted paragraphs, images, tables, colored backgrounds, branded logos, buttons, and other visual components.

An HTML email from an online retailer, for example, might contain a company logo, a product image, a short description, a price, and a clearly visible shopping button.

HTML gives businesses greater control over how messages appear, although different email clients may render the same design differently.

Advantages of HTML emails

Brand consistency: Businesses can use their logos, colors, fonts, and visual identity.

Visual storytelling: Images and product layouts can help explain offers or demonstrate products.

Scannability: Headings, spacing, and visual hierarchy can help readers locate important information.

Clear calls to action: Styled buttons can make actions such as registering, purchasing, or downloading easier to identify.

Flexible content: HTML supports newsletters, event invitations, product announcements, and other visually structured messages.

Limitations of HTML emails

HTML emails require more careful design, testing, and maintenance than simple text messages.

Some email clients restrict particular styles or display layouts differently. Images may be blocked by default, and poorly designed messages may become difficult to read on mobile devices.

Complex HTML can also introduce rendering bugs, broken links, or accessibility problems. Large images may increase download time, especially on slower connections.

HTML itself does not automatically cause an email to be classified as spam. Deliverability depends on many factors, including sender reputation, authentication, recipient expectations, content, links, and complaint behavior.

The objective is to use HTML where it improves the reader’s experience rather than adding decoration without purpose.

3. Plain Text vs. HTML: The Main Differences

The most important differences involve presentation, maintenance, and the type of communication being delivered.

Feature	Plain text email	HTML email
Design	Minimal and straightforward	Supports rich visual layouts
Branding	Mostly through wording and signature	Supports logos, colors, and styled elements
Images	No embedded visual layout	Supports images and other visual content
Calls to action	Usually descriptive text links	Can include styled buttons and links
Maintenance	Generally simple	Requires rendering and compatibility testing
Best use cases	Personal messages, direct updates, simple outreach	Newsletters, product announcements, invitations
Accessibility	Simple when structured clearly	Accessible when semantic structure and contrast are handled properly
Deliverability	Not automatically better	Not automatically worse

Neither format guarantees higher engagement or better inbox placement. Results depend on the audience, message, and implementation.

4. Best Practices for Plain Text Emails

Plain text emails work best when they are concise, organized, and written with the recipient’s needs in mind.

Keep paragraphs short

Long blocks of text are difficult to read, particularly on mobile devices. Break your message into short paragraphs that communicate one main idea at a time.

For example, instead of writing a single paragraph containing the entire purpose of an outreach email, introduce yourself briefly, explain why you are contacting the recipient, and offer one relevant next step.

Use descriptive links

When practical, explain what a link contains rather than relying on vague wording.

Instead of:

Click here.

Use:

Read our guide to improving email deliverability: https://example.com/deliverability-guide

Descriptive links help recipients understand what they are about to open.

Use whitespace effectively

Blank lines can separate the greeting, main message, list of points, call to action, and signature. This creates a visual structure without requiring advanced formatting.

Avoid excessive punctuation and capitalization

Writing entire sentences in capital letters or using repeated exclamation marks can appear unprofessional. It may also resemble patterns found in some unwanted promotional messages, although these characteristics alone do not determine spam classification.

Personalize naturally

Use a recipient’s name or reference a relevant detail when the information is accurate and appropriate. Avoid artificial familiarity or pretending to have a relationship that does not exist.

Make the purpose obvious

Readers should understand why they received the email and what action, if any, is requested. Plain text is particularly effective when the message focuses on one clear objective.

5. Best Practices for HTML Emails

HTML emails require attention to design, readability, functionality, and compatibility.

Use a responsive layout

A responsive email adapts to different screen sizes. Since many recipients read email on mobile devices, designs should remain readable on smaller screens.

Use flexible widths, appropriately sized text, and buttons that are easy to tap. Avoid layouts that require excessive horizontal scrolling.

Keep the design simple

A professional email does not need numerous colors, multiple font styles, or several competing calls to action.

A useful structure might include:

1. A recognizable brand header.
2. A clear headline.
3. A short explanation of the message.
4. One primary call to action.
5. Supporting information.
6. Contact and unsubscribe details where applicable.

A simple design can make the main message easier to understand and maintain.

Optimize images

Images should support the message rather than replace essential information.

Compress images to reduce unnecessary loading time, use appropriate dimensions, and include meaningful alternative text when images communicate important information.

For example, an image showing a new product should have alternative text that identifies the product or describes its relevant function.

Avoid putting all essential text inside a single image. Recipients may have images disabled, and screen readers cannot reliably interpret text embedded in images as ordinary document text.

Use readable typography and contrast

Choose fonts that are easy to read and maintain sufficient contrast between text and its background.

Small, low-contrast text can be difficult to read for people with visual impairments or on mobile screens. Buttons should have clear labels, and important links should not depend on color alone to communicate their meaning.

Test buttons and links

Every link and call-to-action button should work as intended. Test destinations before sending a campaign, and verify that the landing page matches the promise made in the email.

Broken links create frustration and can reduce campaign effectiveness.

Include a plain text alternative

Many email marketing platforms allow senders to provide both HTML and plain text versions in the same multipart message.

When supported, this is a useful practice because recipients’ email clients can select an appropriate version. The plain text alternative should communicate the same essential information as the HTML version.

It should not be left as an outdated or unreadable block of text. Update both versions whenever the campaign changes.

6. How Email Format Affects Deliverability

Deliverability refers to the ability of messages to reach recipients’ email systems and, ideally, their inboxes rather than spam or junk folders.

A common misconception is that plain text emails always reach the inbox while HTML emails are more likely to be filtered. There is no universal rule supporting that conclusion.

Modern filtering systems evaluate multiple signals, which can include sender authentication, domain and IP reputation, recipient complaints, sending patterns, link reputation, and message characteristics.

A legitimate HTML newsletter with clean code, useful content, and reputable links can perform well. A deceptive plain text message sent to an unconsenting audience can still be filtered or rejected.

Both formats benefit from the following practices:

• Configure SPF, DKIM, and DMARC appropriately.
• Send messages to recipients who have a legitimate reason to receive them.
• Maintain accurate email lists and remove hard-bounced addresses.
• Honor unsubscribe requests promptly.
• Avoid misleading subject lines and deceptive links.
• Monitor complaint rates and delivery errors.
• Keep sending volumes consistent with audience expectations.

Content format should be selected for the recipient’s experience, not as a shortcut for avoiding spam filters.

7. Choosing the Right Format for Different Email Types

Different messages benefit from different presentation styles.

Cold outreach

Plain text can be effective for personalized business outreach because it allows the sender to focus on the recipient’s situation and the reason for contacting them.

However, a simple HTML format can also work when it improves readability or supports recognizable branding. The important factors are relevance, honesty, and respect for recipient preferences.

Newsletters

HTML is often useful for newsletters because it supports headings, images, article summaries, and clearly separated sections.

A plain text alternative ensures that readers can still access the essential content without relying on the visual layout.

Transactional emails

Messages such as receipts, shipping updates, and password-reset notifications benefit from clarity and predictable structure. A lightweight HTML design can provide branding while keeping the important information prominent.

Security-related messages should avoid misleading links and should make the expected action clear.

Product promotions

HTML can help retailers display product images, descriptions, and purchase buttons. Nevertheless, the message should remain understandable if images fail to load.

Personal and internal communication

Plain text is often sufficient for quick updates, meeting follow-ups, and direct conversations. It reduces design overhead and keeps attention on the information being communicated.

8. Testing and Measuring Performance

Choosing between plain text and HTML should involve testing rather than relying entirely on assumptions.

Businesses can compare performance across similar audiences and campaigns while changing one important variable at a time.

Useful metrics include:

Click-through rate: The percentage of delivered messages that generate tracked clicks, based on the campaign’s defined calculation.

Conversion rate: The proportion of recipients or visitors who complete a desired action, such as making a purchase or registering for an event.

Bounce rate: The percentage of sent messages that cannot be delivered.

Spam complaint rate: The proportion of recipients who report a message as spam, where reliable complaint data is available.

Unsubscribe rate: The proportion of recipients who opt out.

Open rates can offer limited insight, but they are affected by privacy protections and automated image loading. They should not be treated as a definitive measure of reader interest.

When comparing formats, keep the audience, offer, subject line, timing, and call to action as similar as practical. Otherwise, differences in performance may come from factors unrelated to the format.

Also test rendering in common email clients and on mobile devices. A message that looks attractive in one application may display differently elsewhere.

9. Case Study: How a Retail Business Improved Email Campaigns

This is a hypothetical case study created for illustration. The business and performance figures are not independently verified.

Background

BrightStyle, a fictional online clothing retailer, used email marketing to promote new collections, seasonal sales, and customer loyalty offers.

The company initially sent visually elaborate HTML emails featuring large product photographs, multiple promotional banners, and several purchase buttons. Although the campaigns looked attractive on desktop computers, the marketing team noticed that some recipients had difficulty reading them on mobile devices.

Some messages also depended heavily on images to communicate prices and promotions. When images were blocked, the emails became less useful.

The company decided to evaluate whether plain text, HTML, or a combination of both would better support its marketing goals.

Identifying the problems

BrightStyle reviewed its campaign design and identified four issues.

First, the HTML layouts were too complex for smaller screens, making some messages difficult to navigate.

Second, multiple calls to action competed for attention. Readers were presented with several products and offers without a clear primary choice.

Third, the plain text alternative was automatically generated and contained awkward spacing, long tracking URLs, and outdated promotional information.

Fourth, the company had not systematically compared campaign performance across different formats.

The team recognized that the problem was not simply that HTML was ineffective. Rather, the implementation needed improvement.

Actions taken

BrightStyle introduced a simpler HTML template featuring a recognizable logo, one headline, a short introduction, a small selection of product images, and a prominent primary call to action.

The team optimized images, improved text contrast, and ensured that essential product information remained available when images were disabled.

It also revised the plain text alternative to include the same offer, relevant product details, descriptive links, and a clear closing message.

For customer-service updates and personalized loyalty communications, BrightStyle tested shorter text-focused emails. For product launches and visual promotions, it retained HTML layouts.

The company also reviewed its authentication, list hygiene, unsubscribe handling, and complaint data so that email performance would not be judged by design alone.

Illustrative results

Over a six-week testing period, the fictional retailer compared similar campaigns across customer groups.

In this hypothetical scenario, the simplified HTML campaigns achieved a higher click-through rate than the previous complex templates. Text-focused loyalty messages also generated more replies in selected customer segments.

The team observed fewer customer complaints about mobile readability. However, it did not assume that every improvement resulted from the change in format because content relevance and layout were changed at the same time.

The business continued testing different designs rather than declaring one format universally best.

Lessons learned

BrightStyle’s experience demonstrates three important principles.

First, design complexity does not automatically improve results. A simpler HTML email can be more effective than a crowded layout.

Second, plain text and HTML serve different communication needs. A personal loyalty message may benefit from a direct, conversational style, while a product launch may require images and structured information.

Third, testing both versions provides stronger evidence than relying on marketing assumptions. Businesses should measure outcomes that matter, including clicks, conversions, complaints, and customer satisfaction.

10. Building a Balanced Email Strategy

For many organizations, the most practical strategy is not to choose one format permanently. Instead, they can use plain text and HTML according to the purpose of each message.

An effective workflow begins by identifying the recipient and the objective. The sender then selects a format that makes the message easy to understand and act upon.

For an HTML campaign, the team should check the design, image loading, accessibility, mobile layout, and links. It should also create a useful plain text alternative.

For a plain text campaign, the team should review paragraph length, spacing, link clarity, tone, and the prominence of the main request.

Both formats should undergo quality checks before sending. Businesses should also monitor campaign performance over time and update their approach as recipient preferences change.

Most importantly, email should be useful even when the recipient’s device, application, or accessibility settings differ from the sender’s expectations.

The History of Best Practices for Plain Text vs. HTML Emails

Introduction

Email has developed from a simple method of exchanging electronic messages into one of the world’s most important communication and marketing channels. Throughout this evolution, one question has remained relevant: should an email be written in plain text or designed using HTML?

Plain text emails contain unformatted text, while HTML emails can include images, colors, headings, tables, buttons, and other visual elements. Both formats have played important roles in the history of digital communication. Plain text dominated early email systems because it was simple, reliable, and compatible with the technology available at the time. HTML email later became popular as internet access expanded and businesses began using email for advertising, newsletters, and customer engagement.

However, the introduction of HTML also created challenges involving compatibility, accessibility, security, and deliverability. Over time, email marketers learned that attractive design alone does not guarantee success. Effective email communication requires a balance between visual presentation, readability, technical reliability, and recipient expectations.

This article explores the historical development of plain text and HTML emails, explains how best practices have changed over the years, and examines the lessons businesses can apply to modern email marketing.

1. The Early History of Email and Plain Text Communication

The history of email began before the modern internet became widely available. During the 1960s and early 1970s, computer users exchanged messages through systems connected to individual computers and larger networks.

One important milestone occurred in 1971, when Ray Tomlinson developed a network email application that helped establish the use of the @ symbol to separate a user’s name from the destination computer. His work contributed to the development of the email system that became familiar to later generations.

Early email systems were designed primarily to transfer readable text. Computing resources were limited, network connections were less advanced, and different systems did not necessarily support the same formatting features.

Consequently, plain text was the natural choice. Messages generally consisted of simple text characters, and recipients could read them without requiring a sophisticated rendering engine.

This simplicity offered several advantages. Messages were lightweight, relatively easy to transmit, and compatible with a wide range of computer systems.

The earliest email users were not primarily concerned with branding, product images, or promotional layouts. Their main priorities were exchanging information, coordinating work, and communicating efficiently.

Although modern email marketing has introduced more complex requirements, these original principles remain valuable. Clear writing, concise messages, and reliable delivery are still central to effective email communication.

2. The Growth of Internet Access During the 1980s

During the 1980s, electronic messaging became increasingly important in universities, research institutions, businesses, and other organizations connected to computer networks.

Email systems became more useful as network infrastructure improved. Nevertheless, compatibility remained a significant concern because different computers and software applications handled characters and message formatting differently.

Plain text helped address these challenges. Since messages did not depend on complex visual elements, recipients could often read them across different systems with fewer formatting problems.

The development of standards for email message formatting also helped improve interoperability. The Multipurpose Internet Mail Extensions standard, commonly known as MIME, emerged in the early 1990s and enabled email to carry different types of content, including non-ASCII text and multimedia attachments.

MIME became an important foundation for later HTML email because it allowed messages to contain multiple content types.

During this period, the practical advice for sending email was straightforward: write clearly, keep messages simple, and avoid unnecessary formatting that might not display correctly for every recipient.

These early practices established the technical foundation for the more sophisticated email formats that followed.

3. The Emergence of HTML Email in the 1990s

The 1990s transformed digital communication. The World Wide Web became increasingly popular, graphical web browsers made online information easier to access, and businesses began exploring new ways to communicate with customers through the internet.

HTML, which had originally been developed to structure documents on the web, gradually became part of email communication.

HTML emails allowed senders to create messages that looked more like web pages than traditional text notes. Businesses could introduce logos, product photographs, colored headings, promotional banners, and formatted links.

This development was particularly attractive to marketers. Instead of sending a simple message announcing a product, a retailer could display product images, descriptions, and purchasing information directly inside the email.

Newsletters also benefited from HTML. Publishers could separate articles into sections, use visual headings, and create layouts that resembled printed magazines.

However, HTML email was not immediately consistent across email clients. Different applications supported different features, and some displayed messages incorrectly.

Designers had to learn that email clients did not necessarily behave like web browsers. Layouts that worked in one environment could break in another.

As a result, early HTML email best practices focused on maintaining compatibility, limiting unnecessary complexity, and ensuring that essential information remained understandable.

4. The Expansion of Commercial Email Marketing

As internet access expanded during the late 1990s and early 2000s, email became an increasingly attractive marketing channel.

Businesses could communicate with large audiences at relatively low distribution costs. Retailers promoted products, publishers distributed newsletters, and service providers sent updates to customers.

HTML email became popular because it offered greater control over branding and presentation. Companies could create recognizable visual identities across campaigns and use product images to attract attention.

However, the growing use of promotional email also introduced problems.

Some marketers created messages filled with banners, bright colors, oversized text, and competing calls to action. Others relied heavily on images, leaving recipients with little useful information when images failed to load.

These experiences helped establish an important lesson: visual design must support the message rather than overwhelm it.

Plain text continued to serve a valuable purpose. Personal correspondence, direct sales communication, account notifications, and brief announcements often benefited from a simpler format.

The best choice increasingly depended on the objective of the email. HTML was useful for visually structured communication, while plain text remained practical for direct, information-focused messages.

5. Spam, Security, and the Evolution of Email Best Practices

The growth of commercial email coincided with the expansion of unsolicited bulk messaging, commonly known as spam.

As spam increased, email providers introduced filtering systems to protect users from unwanted advertisements, fraudulent offers, and malicious content.

Some early filters relied heavily on predefined rules, suspicious phrases, and recognizable message patterns. Over time, filtering systems incorporated more sophisticated methods of evaluating email.

This development affected both plain text and HTML senders.

HTML messages containing misleading links, deceptive formatting, or suspicious code could raise security concerns. Plain text messages could also be filtered if they came from an untrusted sender, contained suspicious links, or generated excessive complaints.

It became clear that choosing plain text did not automatically guarantee inbox placement.

Businesses gradually learned to consider several factors together: sender reputation, list quality, authentication, content relevance, and recipient expectations.

Best practices also evolved to discourage deceptive presentation. Subject lines needed to represent the message accurately, and links needed to lead to legitimate destinations.

The historical lesson is that email format should never be treated as a substitute for responsible sending practices.

6. The Rise of Email Marketing Platforms in the 2000s

During the 2000s, email marketing platforms made campaign creation more accessible to businesses that lacked specialized technical teams.

Many platforms introduced visual editors, ready-made templates, subscriber management, scheduling tools, and campaign analytics.

These tools reduced the technical knowledge required to create HTML emails. Marketers could build newsletters and promotional campaigns using predefined layouts rather than writing all the HTML manually.

At the same time, automation increased the importance of consistent design and reusable templates.

Businesses began creating different messages for different purposes, including welcome emails, order confirmations, promotional campaigns, and customer newsletters.

Plain text remained useful for personal communication and text-focused messages, but HTML became a standard option for many commercial campaigns.

The widespread availability of templates also introduced a new challenge: marketers sometimes focused more on appearance than on the recipient’s experience.

A template could look professional while containing too much text, too many images, unclear calls to action, or links that were difficult to understand.

As email marketing matured, effective practice shifted toward purposeful design. Templates needed to be readable, consistent with the brand, and appropriate for the campaign’s audience.

7. Mobile Devices Changed Email Design

The expansion of smartphones and mobile email applications during the late 2000s and 2010s fundamentally changed how email design was approached.

Previously, many designers primarily considered how messages appeared on desktop computers. Mobile devices introduced smaller screens, touch-based navigation, and different reading conditions.

HTML emails designed for large monitors could become difficult to read on phones. Small text, wide tables, tiny buttons, and oversized images created frustrating experiences.

This encouraged the development of responsive email design, which adapts a message’s layout to different screen sizes.

Modern mobile-friendly email practices include using flexible layouts, readable text, appropriately sized buttons, and concise content.

Plain text naturally avoids many layout problems because it does not rely on columns or complex visual elements. However, long unbroken paragraphs and poorly formatted URLs can still make plain text difficult to read on mobile devices.

The historical lesson is that simplicity must be intentional. Even a plain text email benefits from short paragraphs, clear spacing, and a logical structure.

8. Accessibility Became a Greater Priority

As email became central to business, education, healthcare administration, and public communication, accessibility received greater attention.

Accessibility means designing communication so that people with different abilities can understand and use it.

Plain text can support accessibility because it presents information in a straightforward form. Nevertheless, it still needs clear wording, readable organization, and meaningful link descriptions.

HTML can also be accessible when developers use appropriate structure, sufficient color contrast, descriptive alternative text, and links or buttons that work with assistive technologies.

Problems arise when HTML emails depend entirely on images to communicate essential information or use visual styling that makes text difficult to distinguish.

For example, an email that displays a promotional offer only inside an image may become less useful when the image is blocked or cannot be interpreted by a screen reader.

Over time, accessibility best practices increasingly emphasized making important information available as actual text, organizing content logically, and avoiding unnecessary visual barriers.

This shift reinforced the idea that successful email design must work for different recipients, devices, and reading environments.

9. The Development of Multipart Email Messages

One important technical practice is the use of multipart email messages that provide both plain text and HTML versions.

In a properly constructed multipart message, the sender includes alternative representations of the same essential content. A compatible email client can then choose the version that best suits its capabilities or preferences.

This approach combines the simplicity of plain text with the design flexibility of HTML.

For example, a retailer can send a visually appealing HTML newsletter while also providing a plain text version containing the same headline, offer details, links, and essential instructions.

The plain text alternative should not be treated as an afterthought. If the HTML version changes, the text version should be updated too.

It should also avoid unnecessary formatting artifacts, confusing tracking URLs, or content that no longer matches the campaign.

Multipart messages do not guarantee better inbox placement, but they offer a practical way to improve compatibility and ensure that important information remains available in different viewing environments.

10. Modern Best Practices for Plain Text Emails

Today, plain text remains relevant because many communication tasks do not require advanced visual design.

Effective plain text emails generally follow several principles.

Write with a clear purpose. The recipient should quickly understand why the message was sent.

Keep paragraphs short. Large blocks of text are difficult to scan on mobile screens.

Use spacing thoughtfully. Blank lines can separate the greeting, main points, call to action, and signature.

Make links descriptive. Whenever practical, explain what the recipient will find at a destination instead of using vague instructions.

Personalize honestly. Refer to the recipient’s interests or previous interactions only when the information is accurate and relevant.

Avoid unnecessary formatting substitutes. Excessive symbols, repeated punctuation, and artificial text decoration can make messages harder to read.

Plain text is particularly appropriate for direct correspondence, concise business outreach, simple updates, and messages where the content matters more than visual presentation.

11. Modern Best Practices for HTML Emails

HTML emails remain valuable for newsletters, product launches, event invitations, and other communication that benefits from visual structure.

However, modern best practices emphasize usability rather than decoration alone.

First, keep layouts simple and responsive. The message should remain readable on both desktop and mobile devices.

Second, use images to support the message rather than replace essential information. Include meaningful alternative text where appropriate and ensure that important details remain understandable when images are disabled.

Third, use a clear visual hierarchy. Headings, paragraphs, and calls to action should help readers understand the message without competing for attention.

Fourth, maintain sufficient contrast and readable font sizes.

Fifth, test links, buttons, and rendering across common email clients.

Finally, provide a useful plain text alternative when the sending platform supports multipart messages.

HTML should make the message easier to understand, not merely more visually complicated.

12. The Influence of Artificial Intelligence and Modern Filtering

In recent years, email services have continued to improve their ability to identify spam, phishing, and suspicious content.

Modern filtering can consider sender authentication, domain reputation, link destinations, sending patterns, recipient complaints, and characteristics of the message itself.

This means that neither plain text nor HTML automatically has a deliverability advantage in every situation.

A plain text email can still be filtered if it contains deceptive claims, suspicious links, or unwanted content. An HTML newsletter can perform well when it comes from a trustworthy sender and provides useful information to an appropriate audience.

Artificial intelligence has also made it easier for attackers to produce polished messages, so spelling mistakes and poor grammar are no longer reliable indicators of suspicious email on their own.

For legitimate senders, the most durable practices remain accurate subject lines, secure links, correct authentication, relevant content, clean mailing lists, and respect for recipient preferences.

The evolution of filtering reinforces the importance of sending emails that recipients genuinely expect and want to receive.

13. Historical Lessons for Businesses

The history of plain text and HTML emails offers several lessons for organizations developing modern communication strategies.

First, technology changes, but clarity remains essential. Early email users depended on straightforward text, and modern readers still value messages that communicate their purpose quickly.

Second, visual design should serve a specific function. HTML is useful when images, layout, and branding make the content more understandable. Decoration that distracts from the message can reduce its effectiveness.

Third, compatibility matters. The development of HTML email repeatedly demonstrated that messages must work across different devices and applications.

Fourth, accessibility benefits everyone. Clear structure, readable text, and descriptive links improve the experience for a broad range of recipients.

Fifth, deliverability depends on more than formatting. Sender reputation, authentication, recipient expectations, and content quality all influence whether email communication succeeds.

Finally, testing is more reliable than assumptions. Businesses should compare performance across relevant audience groups and evaluate clicks, conversions, complaints, unsubscribes, and other meaningful outcomes.

Conclusion

The history of best practices for plain text versus HTML emails reflects the wider evolution of digital communication. Plain text dominated early email because it was simple and compatible with limited technology. The emergence of HTML email during the 1990s introduced visual branding and richer presentation, while the expansion of email marketing platforms made sophisticated campaign design accessible to more businesses.

The growth of spam, the arrival of mobile devices, increased attention to accessibility, and advances in security filtering all influenced how emails are created today.

Modern email communication benefits from using both formats appropriately. Plain text remains effective for direct, concise messages, while HTML is useful when visual structure improves the recipient’s experience. Providing both versions can support compatibility and preserve essential information.