Most cold email advice tells you what to write. Nobody talks about what format to send it in. We test three email formats on every campaign: Plain Text, Text plus Image, and Full HTML. The results vary dramatically depending on who you are targeting.
Format A: Plain Text
A plain text email looks like something a real person typed. No logos, no designed headers, no HTML formatting. Just words.
This format consistently performs best when targeting founders, CEOs, and C-suite executives. These people receive dozens of marketing emails daily. A designed email screams "mass campaign." A plain text email feels like a personal note from someone who took the time to write directly to them. We typically see 15 to 25% higher reply rates from Plain Text compared to HTML when targeting senior decision-makers. This hybrid approach uses plain text styling but includes one visual element: a screenshot of a relevant case study result, a chart, or a product demo image. The text does the selling. The image provides proof. This format works well for technical buyers and mid-level managers who need visual evidence to justify taking a meeting. A screenshot showing "140 qualified leads generated for a Fortune 500 manufacturer" is more persuasive than describing it in text alone. Designed emails with branded headers, styled CTAs, and formatted layouts. These work best for high-volume segments where brand recognition matters, such as event invitations, product launches, or campaigns targeting audiences who already have some awareness of your company. For cold outreach to prospects who have never heard of you, HTML emails generally underperform. They trigger promotional tab sorting in Gmail and signal "marketing email" rather than "personal message." We do not decide in advance. We test. Every campaign launches with all three formats sent to split segments of the same prospect list. After two weeks of data on open rates, reply rates, and meeting conversion, we identify the winning format for that specific audience and scale it across the remaining campaign. The winning format changes based on industry, seniority level, and geography. What works for targeting CFOs in manufacturing will not work for targeting marketing directors in SaaS. Testing is the only reliable way to find out.Format B: Text plus Image
Format C: Full HTML
How we decide which format to use
