You're probably overthinking this. You've sent out a few HTML campaigns with nice formatting, colors, and a branded signature. The open rates look fine. Then you try plain text - just black text on white background, no images, no styling - and something weird happens. Sometimes it performs better. Sometimes worse. And you have no idea why.

The problem is that most cold email advice treats HTML and plain text like it's purely a style choice. It's not. It's a technical rendering problem that changes how your email appears in different inboxes, which directly affects whether someone opens it or marks it as spam.

Why rendering matters more than you think

When you send HTML email, your email client (Gmail, Outlook, Apple Mail, etc.) has to interpret all those tags and CSS. Each one renders slightly differently. A broken HTML email looks broken - misaligned text, missing images, strange spacing. A prospect sees a broken email and either deletes it or marks it as spam. You lose the deal before they even read your opening line.

Plain text has zero rendering risk. There's nothing to break. It looks identical everywhere - Gmail, Outlook, mobile, desktop. No images fail to load. No CSS gets stripped. It's just text.

But here's what most people miss: plain text also signals "I'm not a mass marketer." HTML emails with images, branded headers, and colored buttons are what automated marketing platforms send. Plain text looks like an actual person wrote it in Gmail and hit send. In cold email, that perception matters.

The response rate difference (what we actually see)

We've tested this across hundreds of campaigns for service businesses and agencies. The data is consistent:

Plain text wins. Not always by a huge margin, but consistently. The reason isn't magic - it's deliverability plus perception. HTML emails have more technical ways to fail. They trigger more spam filters. And when they do land in the inbox, they feel less personal.

Now, there's a caveat. If you're sending to warm leads or existing contacts, HTML with some light formatting can perform fine or even better because they already recognize your brand. But for cold prospects? Plain text is the safer play.

What plain text cold email actually looks like

Here's the thing most people get wrong about plain text - they think it has to be boring. It doesn't. It just has to be simple.

A good plain text cold email for a service business looks like this:

Hi Sarah, Quick thought - I noticed you're handling demand gen for SaaS companies. We've worked with 3 companies in that space over the last 8 months, and every single one had the same bottleneck: their email infrastructure was set up wrong, so their cold email was getting spam filtered before it even hit inboxes. Since you probably have the same setup issue, I figured it was worth a 15-minute call to show you what we're seeing. Does next Tuesday or Wednesday work? Thanks, Jack

No formatting. No line breaks for emphasis. No colored text. No signature image. Just one person to another. Notice that it still has structure - opening line, pattern interrupt, value statement, call to action. The plain text format doesn't kill any of that. It just removes the distractions.

When HTML actually makes sense

HTML isn't useless. There are specific situations where it makes sense:

The key rule: if you're going to use HTML, test how it renders in Gmail and Outlook with images disabled. Because maybe 30% of your recipients will have images turned off by default. If your email says "Click the button below" and there's no button visible because images didn't load, you've just wasted the email.

Plain text doesn't mean ugly signature

One last thing - plain text emails can have a signature. It just has to be plain text too. Here's what we use:

Jack Thompson Founder, BEC Growth Phone: (555) 123-4567 Website: becgrowth.com

That's it. No image, no fancy formatting, no hidden links. You can include it in every email without adding rendering risk. And if someone wants to reach you, they have a phone number and website they can actually click on from any email client.

One more rendering consideration

If you do send HTML, understand that cold email rendering in Gmail and Apple Mail each have their own quirks. Gmail strips certain CSS properties. Apple Mail renders things differently. Outlook has its own interpretation. If you're not testing across all three, you're sending broken emails to someone's inbox and never knowing it.

This is exactly why plain text wins in cold email. There's nothing to break. There's no rendering to worry about. You send text. It appears as text. Everyone sees the same thing.

Start with plain text. Test it. Get your baseline. Then if you want to test HTML for specific segments (warmer prospects, follow-ups, etc.), do it with the knowledge that you're trading simplicity for a slight risk.

The gap between knowing this and running it

Understanding that plain text performs better is one thing. Building a cold email system that actually tests both formats properly, tracks which works for your specific list, and knows when to switch to HTML for warm prospects - that's a different problem. Most agencies figure this out through trial and error over months. If you want the infrastructure and process already built, that's what we do at BEC Growth.

Related Guides