The Impact of HTML vs Plain Text Emails on Deliverability
The HTML vs plain text debate has a clear winner in cold email: plain text wins for deliverability, open rates, and reply rates.
The HTML vs plain text debate has a clear winner in cold email: plain text wins for deliverability, open rates, and reply rates.
What HTML means in email
Even a "simple" email with bold text, colored fonts, or a designed signature is HTML. Your email client translates these visual elements into HTML code that the receiving server evaluates. The more complex the HTML, the more closely it resembles marketing email — and the more likely it is to be filtered.
Why plain text wins for cold email
Plain text emails have minimal code. They look like personal messages. They pass content filters more easily because they lack the patterns associated with bulk commercial email. Every design element you add — bold, italic, colored text, tables, images, buttons — increases HTML complexity and deliverability risk.
The data
Multiple cold email performance studies show that plain text emails achieve higher inbox placement rates and higher reply rates than HTML-styled emails. The difference is typically 10-20% in reply rate, primarily because more of the emails reach the inbox in the first place.
When HTML is necessary
Some cold email tools add minimal HTML for tracking or formatting by default. This is generally fine as long as you are not adding your own visual styling on top. The goal is to keep the email as close to what a regular person would send from their Gmail or Outlook client as possible.
Practical implementation
Write your emails in the plain text editor if your tool offers one. Do not apply formatting — no bold, no italics, no bullet points, no colored text. Do not use email templates with designed headers or footers. Do not include images or HTML buttons. Just write text. Your email should be indistinguishable from a personal email a colleague might send. That is the formatting standard that achieves the best deliverability.
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