HTML emails look better. Plain-text emails actually get read.
That gap between visual polish and actual performance is one of the more counterintuitive realities of B2B email marketing. Most marketing teams invest real effort in branded templates, custom fonts, and pixel-perfect layouts. Those same templates are often quietly hurting deliverability, open rates, and response rates at every step.
This post explains why, and how to test the plain-text approach on your own nurture sequences.
Before an email reaches a human inbox, it passes through several layers of filtering. Internet service providers, spam filters, and inbox categorization systems all make decisions about where a message lands: primary inbox, promotions tab, spam folder, or outright rejection.
These systems look at multiple signals. Image-to-text ratio. The number of links in the message. The presence of tracking pixels. The use of HTML tables and CSS styling. Domain reputation. Sending infrastructure.
A heavily designed HTML email hits several of these signals at once. It has a low text-to-image ratio if images are present. It often has multiple tracked links. It uses HTML formatting that patterns closely to what spam systems see in bulk commercial email.
Plain-text strips all of that out. No images. No tables. No tracking pixels embedded in image tags. Just text, structured the way a real person would write an email from their work account.
Inbox algorithms have been trained on billions of emails. They're reasonably good at distinguishing "a company sending their newsletter" from "a person writing to another person." Plain-text looks more like the latter, which is exactly the behavior they're trying to preserve.
The pattern is consistent across B2B nurture testing: plain-text versions of the same email outperform HTML versions on deliverability and open rate, sometimes significantly.
The mechanism is straightforward. Better deliverability means more messages land in the primary inbox instead of promotions or spam. More primary inbox placement means higher open rates, because primary inbox open rates run substantially higher than promotions tab open rates. Higher open rates improve domain reputation, which further improves deliverability. It compounds.
The effect is strongest for cold outreach and early-stage nurture sequences where you're trying to establish a relationship with someone who doesn't yet have strong familiarity with your brand. It's less decisive for audiences that already engage regularly with your emails, where the promotional context is expected and accepted.
Plain-text isn't the right answer for every use case. There are contexts where HTML formatting is appropriate and even expected.
Product announcements and feature releases often benefit from visual formatting. Users who have opted in specifically to receive product updates are in a different relationship with your emails. The promotional format is part of the signal.
Marketing newsletters with a defined publication format can build their own engagement patterns over time. Consistent visual branding in a weekly newsletter becomes part of the value proposition.
The highest-value test is on your early lifecycle nurture sequences: the emails that go out in the first 7-30 days after signup, the sequences designed to educate new users, the outreach to trial users who haven't activated yet. These are the emails where deliverability matters most and where a plain-text format is most likely to move the needle.
The test setup is simple. Take an existing nurture sequence. For each email, create a plain-text version with identical subject line and body copy. Send the two versions to randomly split segments of equivalent size.
Measure primary inbox placement rate if your ESP provides it. Measure open rate. Measure click rate. Measure reply rate if replies are a goal.
Run the test long enough to accumulate statistical significance. For most B2B email programs, that means at least several hundred sends per variant before drawing conclusions.
One note on tracking: plain-text emails typically don't support pixel-based open tracking, since open tracking relies on an invisible image pixel loading. You may need to rely on click tracking alone, or use a different measurement approach. That loss of open tracking data is one reason teams hesitate to test plain-text. It's worth it.
Your beautifully designed email template may be working against you in the place that matters most: getting to the inbox at all. Test plain-text on your highest-stakes sequences first. The results will tell you whether to go further.