What is plain text vs. HTML email?

You're looking at two ways to structure an email: plain text (just words, no formatting) and HTML (the web page version with colors, images, links, fonts).

Here's the practical difference: plain text emails look like what you'd type in Notepad. No bold, no images, no clickable buttons. HTML emails look like web pages. They can have brand colors, formatted text, inline images, and styled calls to action.

Most emails you get today are HTML, even the ones that look plain. Your inbox renders them as HTML, but the sender designed them to look minimalist. True plain text (the kind that's only plain text, no HTML fallback) is rare because modern ESPs default to sending both formats in what's called a multipart/alternative message. The inbox picks which version to show.

When to use plain text

Plain text works best for personal, one-to-one communication. Password resets, order confirmations, and internal company emails often send plain text because it feels direct and urgent. Some newsletters intentionally use plain text to feel more personal and less "marketing-y." Plain text also bypasses image-blocking entirely (there are no images to block).

Deliverability-wise, plain text has a slight reputation advantage in certain contexts. Spam filters treat plain text as lower-risk for phishing because there's less room to hide malicious links behind buttons or images. But this advantage disappears if your content is spammy or your authentication is broken.

When to use HTML

HTML is the default for marketing emails, newsletters, and anything where you want brand consistency or visual design. You can include your logo, format text for readability, add buttons that look clickable, and track image opens. Most ESPs like Mailchimp, Klaviyo, and Brevo assume you're sending HTML and provide drag-and-drop editors for it.

And the trade-off: HTML emails are more complex to build, render differently across email clients (looking at you, Outlook), and require you to include alt text for images if the recipient has images turned off. If your HTML is broken or bloated, it can hurt deliverability or make the email unreadable.

The multipart reality

Still most ESPs send both versions in the same message using a MIME multipart/alternative structure. The recipient's email client picks which one to display. If they block images or prefer plain text, they see the plain text version. If they allow HTML, they see the styled version.

This is why "plain text vs. HTML" is less of a binary choice than it seems. You're usually sending both. The question is whether you design the plain text version intentionally or let the ESP auto-generate it by stripping the HTML (which often looks terrible).

How to decide

If you're sending transactional emails (receipts, password resets, shipping updates), plain text or minimal HTML is the norm. If you're sending newsletters or promotional campaigns, HTML is expected. If you want to stand out in a crowded inbox, some senders experiment with plain-text-style HTML (looks plain, but still tracks opens and allows links).

Check what your ESP sends by default. Most marketing platforms send multipart, but some transactional services like Postmark let you choose per message. If you're coding your own emails, you control the MIME structure entirely.

Want to see what your emails actually look like in both formats? Send yourself a test and check the raw source with our Source Analyzer. It'll show you whether you're sending plain text, HTML, or both.