Plain text is clean and universally supported, but at some point you want your emails to look like your brand. HTML lets you style headings, bold or italicize key phrases, create buttons, place images, add columns, and track clicks. This guide explains exactly how to switch from plain text to HTML in Gmail, Outlook, and Apple Mail, how to convert an existing message into HTML code, how to design and send professional HTML emails with popular tools, and what to do when a client forces plain text. You will get step-by-step clicks, ready-to-paste code snippets, and practical troubleshooting so you can move from black-and-white text to polished, on-brand email without getting lost in the weeds.
The goal is practical mastery. You will start with quick switches in the most common email clients, then learn how to convert content you already wrote into HTML, and finally build a robust workflow you can rely on for campaigns, newsletters, and transactional messages.
Plain Text vs HTML: What Changes When You Flip the Switch
Plain text emails contain only characters. They cannot include color, fonts, images, links with anchor text, or layout. Every line break is literal and every URL shows as raw text. Because there is no formatting, plain text is fast, accessible, and widely deliverable, and many servers and security tools love it for those reasons.
HTML emails use HTML markup and CSS styling to format content. They support headings, colors, fonts, bold/italic/underline, lists, tables, buttons, images, and sometimes animated GIFs. They can also track opens and clicks when sent through an email platform. The trade-offs are that design choices must respect the limits of email clients, CSS must be simplified and mostly inlined, and some recipients or corporate gateways block images and remote assets until a user opts in.
If you send marketing or customer-facing messages, HTML is usually the right default. If you send alerts to engineers or automated logs to servers, plain text may still be the best choice. Many senders include both formats in one message using a multipart/alternative structure so a recipient sees the version their client prefers.
The Quickest Fixes First: Turn On HTML in Popular Email Clients
Gmail on the web
Gmail’s composer is rich-text by default. If your compose window looks like plain text, you likely disabled formatting or pasted as plain text.
Steps to enable formatting:
- Click Compose to open a new message.
- If you see a minimal toolbar, click the capital A icon to show formatting.
- Use the toolbar to apply bold, italics, underline, color, lists, alignment, and insert links or images.
- If you previously toggled plain text mode, open the three-dot menu in the composer and uncheck Plain text mode.
Pasting with formatting:
- Copy formatted text from a source that supports rich text, such as a document or page.
- In Gmail, paste normally to retain formatting.
- If you use Shift+Ctrl+V (Windows) or Shift+Cmd+V (Mac), Gmail pastes as plain text, so avoid that when you want HTML styling preserved.
Sending hand-coded HTML through Gmail’s composer can be tricky because the editor sanitizes markup. If you need pixel-perfect templates, use a dedicated email platform or a browser extension that safely injects HTML, or paste styled content from an HTML editor that Gmail accepts.
Gmail mobile apps (iOS and Android)
The mobile composer supports basic rich text: bold, italic, underline, lists, and links.
- Tap Compose.
- Type your text, then long-press to select a word or phrase.
- Choose Format and pick the style you want.
- Insert links from the context menu.
For complex layouts, build emails on desktop or in a marketing platform and send from there.
Outlook for Windows (current Outlook / Microsoft 365)
Outlook supports Plain Text, Rich Text (RTF), and HTML. Use HTML.
- New Email.
- Open the Format Text tab on the ribbon.
- In the Format group, pick HTML.
- Compose using the Message tab formatting tools. Insert pictures, tables, and shapes as needed.
To make HTML the default for all new messages:
- File → Options → Mail.
- Under Compose messages, set Compose messages in this format to HTML.
- Save.
If you reply to a plain-text thread, Outlook may keep the format. Switch to HTML in Format Text before sending if you want styling.
Outlook for Mac
- New Email.
- From the Message menu, ensure the message is in HTML mode. In recent versions, HTML is the default and the formatting bar appears automatically.
- Use the formatting tools to style and insert links or images.
Set HTML as the default in Outlook preferences if needed.
Outlook on the web (Outlook.com / Exchange Online)
- New message.
- The toolbar shows formatting controls by default.
- If you see plain text, open More formatting options and switch to HTML.
- Use the editor to style, insert images, and create tables.
Apple Mail on macOS
Apple Mail distinguishes between Plain Text and Rich Text (which corresponds to HTML on send).
- Mail → Settings (or Preferences) → Composing.
- Ensure Message format is Rich Text.
- Close settings.
Per-message:
- New Message.
- From the Format menu choose Make Rich Text if it shows Make Rich Text; if it shows Make Plain Text, you are already in rich text mode.
- Use the formatting bar to apply styles, insert images, and build lists.
When replying to a plain-text message, Mail may continue in plain text to match the thread. Choose Make Rich Text to switch.
Apple Mail on iPhone and iPad
The iOS composer supports basic styling.
- New Message.
- Type your content.
- Select text and tap BIU or the formatting button above the keyboard.
- Choose styles and insert links.
- Inline images are inserted from the photo picker or Files.
For full-fidelity HTML newsletters, design on desktop or use a mail platform.
Converting Existing Plain Text Content Into HTML
Sometimes you wrote the message already, or you exported content from an app in plain text and need to convert it into an HTML email that looks polished. Here is a simple path you can use without specialized tools.
Step 1: Clean the text
Remove extra spaces, straighten quotes if you like, and ensure paragraphs are separated by blank lines if that is how you want them to appear.
Step 2: Wrap paragraphs in basic HTML
Use simple tags that render safely across clients. Avoid modern CSS layout and rely on tables for structure if you need columns.
Step 3: Inline critical styles
Many email clients strip or rewrite CSS in the head. Inline key styles on tags or use a tool that inlines CSS automatically before sending. If you build with an editor like Stripo or BeeFree, their export process will inline styles for you.
Step 4: Replace plain URLs with links and buttons
Turn raw URLs into clickable anchor tags. For a button, use a styled link because real buttons are not widely supported in email.
Step 5: Test in multiple clients
Send to a few accounts you control on different devices. Confirm spacing, fonts, link colors, and dark-mode fallback are acceptable.
Turning a Plain-Text Reply Into HTML Without Losing Quoting
Replies often inherit the format of the original. If a customer wrote in plain text and you want to reply in HTML with links or screenshots, switch modes before you type.
Outlook:
- Open the plain-text message and click Reply.
- Format Text → HTML.
- Compose your response. Outlook converts the quoted original into a styled block. Adjust the quote style under File → Options → Mail if the blue bar or prefix characters are too heavy.
Apple Mail:
- Reply.
- Format → Make Rich Text.
- Insert images or links normally. Mail respects the quoted original while allowing your HTML styling.
Gmail:
- Reply.
- Click the A formatting icon to show the toolbar.
- Paste images or links and style your text. Gmail keeps the quoted part in a collapsible block.
If your organization enforces plain text on replies to certain addresses, ask your admin about exceptions or reply with a separate HTML message that references the ticket number.
Building and Sending HTML Emails with Editors and Platforms
If you need more than quick formatting, dedicated builders save hours and reduce rendering surprises.
Drag-and-drop editors
Tools like Mailchimp, BeeFree, Stripo, and Constant Contact let you assemble blocks—hero image, headline, paragraph, two-column features, button—and export HTML that is already inlined and tested across clients. You can import the HTML into other platforms or send directly from those services.
Design apps
Canva can export email headers and graphics sized to common widths like 600px. Combine with a basic HTML template and you have a fast, branded newsletter. Keep text live when possible rather than baking all copy into images so your message remains searchable and accessible.
Code editors
If you prefer full control, code the HTML with simple table layouts, inline CSS, and tested patterns. Avoid JavaScript, external fonts, video tags, position fixed, and complex selectors. Re-use a boilerplate you trust and keep a personal checklist for images, alt text, and fallbacks.
Testing suites
Services like Litmus and Email on Acid let you preview across dozens of clients and dark-mode variants. If you cannot use those tools, build a small seed list of personal test accounts across Gmail, Outlook, Apple Mail, iOS, and Android.
Deliverability note
Plain text sometimes lands in the inbox more reliably because it looks less promotional. HTML can be just as deliverable if you keep the code clean, include a plaintext part, avoid spammy phrases, use authenticated sending (SPF, DKIM, DMARC), and keep image-to-text ratio reasonable.
Why Some Servers Force Plain Text and What You Can Do
Security-sensitive environments sometimes convert incoming HTML to plain text or block outbound HTML to reduce risk. If you must send HTML but a gateway strips it, use a marketing platform for external communications instead of a desktop client, or ask your administrator for an exception for a specific sender address. For transactional emails such as receipts or password resets, third-party providers can deliver both HTML and a plain-text fallback in one message so every recipient sees something understandable.
Content and Design Tips That Make HTML Emails Work Everywhere
Write like a human
Short subject lines, clear preview text, and paragraphs that get to the point help both plain text and HTML. If you use storytelling to create curiosity, do it honestly and deliver value in the body. In the same way a headline such as This Dolphin “Trick” Has Fascinated Scientists for Decades pulls interest in a science context by promising a specific mystery and payoff, your subject and first line should set a clear expectation and then answer it cleanly inside the email.
Keep your layout simple
A single column of 600px width remains the safest choice. Two columns can be fine if you stack them vertically on mobile. Avoid three or more columns in email unless you are comfortable with fine-tuning table code.
Use web-safe fonts or host custom fonts with fallbacks
Most email clients do not load custom fonts reliably. Use system fonts like Arial, Helvetica, Georgia, or Segoe UI. If you must use a custom font, include a specific fallback and accept that not all recipients will see it.
Inline CSS
Many clients strip styles in the head. Inline critical styles on each element. Tools and editors can automate this inlining step for you.
Contrast and dark mode
Use sufficient contrast for readability. Test in dark mode. Inlined colors often override dark-mode inversion, but some clients force their own palette. If your brand blue looks too bright on a black background, adjust to a slightly desaturated shade for dark mode only, using the prefers-color-scheme media query and accepting that not all clients honor it.
Alt text and live text
Always include alt text for images. Never put essential copy only in images. Live text scales better, is searchable, and remains visible when images are blocked.
Buttons as links
Build buttons with styled anchor tags and table wrappers if you need precise spacing. Avoid relying on CSS properties unsupported in popular clients.
Test links and tracking
Click every link in a test send. If your platform adds tracking parameters, ensure they do not break your destination URLs. If you are hand-coding UTM parameters, watch for duplicates.
Troubleshooting: Why Your Message Stayed Plain Text and How to Fix It
The HTML option is missing or grayed out: You might be replying to a plain-text message, and the client is respecting the original format. Switch to HTML before typing. In Outlook, use Format Text → HTML. In Apple Mail, Format → Make Rich Text. In Gmail, toggle the formatting bar on and ensure Plain text mode is unchecked in the composer menu.
Your HTML pasted as code instead of rendering: Some composers sanitize input and show angle brackets literally to prevent injection. Compose in a builder and paste the formatted result, not raw HTML. If you must paste raw HTML, use a tool or workflow designed for that client, or send via a marketing platform.
Images are not showing: Many clients block images by default. Ask recipients to add you to their safe sender list, or host images on a reliable CDN with HTTPS and keep file sizes modest. Always include alt text and a plain link as a fallback.
Spacing looks different than expected: Email line height and margin handling vary. Use padding on table cells instead of margins when you need consistent spacing. Test on Outlook for Windows, which uses the Microsoft Word rendering engine and treats margins inconsistently.
Links are the wrong color: Some clients rewrite link colors to their defaults. Inline the color on each link tag. If a mobile client still overrides it for accessibility, accept the override rather than fighting it.
Dark mode inverted your logo: Provide an alternate logo with a transparent background, add a subtle outline or shadow, or use a version with colors that remain visible on dark backgrounds. Some clients rewrite colors, so perfect control is not possible.
Corporate server forces plain text: If outgoing HTML is blocked, use a trusted marketing platform for external campaigns or request a policy exception for a specific sender address. For critical communications, include an attractive plain-text version and a link to a hosted HTML page.
A Maintainable Workflow You Can Keep Using
- Decide your default
Use HTML for branded and customer-facing emails, and include a plain-text alternative when sending through a platform. Use plain text for logs and alerts.
- Create a small library
Keep a minimal HTML boilerplate and a few content blocks you like: two-column features, testimonial, CTA, footer. Reuse and adjust.
- Pick a path
For ad hoc messages, compose in Gmail, Outlook, or Apple Mail with built-in formatting. For newsletters, use a drag-and-drop builder and export the HTML or send directly.
- Test fast
Send to your own Gmail, Outlook, and Apple Mail accounts. Glance on phone and desktop. Fix obvious spacing and color issues before sending broadly.
- Track and learn
If using a platform, monitor opens and clicks and refine. If sending from a mailbox, include a clear link to a landing page you can measure.
Wrap-Up
Switching from plain text to HTML is less about flipping a magic switch and more about choosing the right path for the job. For quick one-offs, enable rich text in Gmail, Outlook, or Apple Mail and style your message right there. For recurring campaigns, use an editor that exports safe, inlined HTML or send through a platform that already handles rendering quirks and tracking. Keep your layout simple, your CSS inlined, your images described with alt text, and your buttons built from links. Include a plain-text version when you send at scale, test across a few clients and devices, and your messages will look sharp without surprising anyone’s inbox.
Once you understand these patterns, converting a plain text email into HTML is just a matter of minutes, and you will have a repeatable workflow you can use every time the message deserves a little design.
FAQ’s
Why can’t I change my email from plain text to HTML?
You are probably in a reply that inherited plain text from the original, or your client is in plain text mode. Switch the format before you type. In Outlook, use Format Text → HTML. In Apple Mail, Format → Make Rich Text. In Gmail, open the formatting bar and ensure Plain text mode is not enabled in the composer menu.
Do all email clients support HTML?
Most modern clients do, but their support for CSS is limited and inconsistent. Outlook for Windows handles CSS differently than Gmail, which differs from Apple Mail. That is why email templates rely on simple tables, inline styles, and cautious use of images.
Which is better for marketing: plain text or HTML?
Both can work. Plain text can feel personal and sometimes lands in the inbox more easily. HTML supports branding, layout, and analytics. Many marketers alternate or blend approaches, using a simple HTML layout that looks close to a personal note but still carries brand colors and tracked links.
How do I convert a long plain-text message into HTML quickly?
Paste the text into an email builder or a simple HTML template and wrap paragraphs in tags. Add headings, links, and a button using the snippets provided above. Inline styles on each element, then test on your own devices.
Can I paste raw HTML into Gmail?
Not reliably. Gmail’s composer sanitizes markup. Use a builder and paste formatted content, or send through a platform designed for HTML campaigns. Some workflows allow safe HTML injection, but they are outside typical end-user features.