Most cold email looks like marketing because it was built by marketers. Logo header, brand colors, a hero image, three call-to-action buttons, a footer full of social icons. It's polished — and it's exactly why it lands in the Promotions tab next to the airline deals and the loyalty-points reminders, unread.
For cold outreach, the format that wins is the one that looks like no format at all: plain text, a few short lines, one soft ask. This guide explains why plain-text-style email out-delivers and out-converts designed HTML for cold sends, where HTML still earns its keep, and how to think about links, images, and light formatting along the way.
Plain text vs HTML email: what actually changes
The difference isn't really about how the email looks — it's about what the email is built from. A plain-text email is mostly words: a greeting, a few sentences, maybe a link. An HTML email is a tiny web page rendered inside the inbox — tables, styles, hosted images, branded buttons, and a wrapper of code the recipient never sees but the spam filter absolutely does.
That hidden code is the whole story. Mailbox providers read the structure of a message, not just its words. A message that's 90% markup with one line of copy and a big image looks like a campaign. A message that's plain prose looks like a human wrote it to one person. For cold outreach — where you have no prior relationship and no opt-in to lean on — looking human is the single biggest lever you have.
Why plain text feels 1-to-1 (and why that wins)
Open your own inbox and look at the emails from actual people — a colleague, a vendor, your accountant. None of them have a banner image or a brand-colored button. They're plain text because the person typed them. Your brain learned that pattern years ago: designed equals broadcast, plain equals personal.
Filters learned the same pattern, because they're trained on how real people send and receive mail. A cold email that mimics a genuine one-to-one note gets the benefit of the doubt. A cold email that mimics a newsletter gets sorted with the newsletters. The merchant on the other end makes the same snap judgment in half a second — a plain note from a name reads like someone reaching out; a designed template reads like an ad they didn't sign up for.
This is why a soft, conversational ask outperforms a hard sell in cold MCA outreach. 'Are you open to seeing some rates?' in three plain lines feels like a question from a person. 'APPLY NOW' under a hero graphic feels like a billboard. Same offer, completely different response — because one respects the format of a real inbox conversation and the other ignores it.
How HTML lands you in the Promotions tab
Gmail's Promotions tab is a graveyard for cold outreach. Mail that lands there isn't technically spam — it's just been quietly filed away from the merchant's primary inbox, where it competes with every coupon and product launch the recipient ignores by default. Open rates there are a fraction of what the primary inbox delivers.
And Gmail decides where to file you largely from format. The signals that scream 'Promotions' are exactly the ingredients of a designed HTML email: image-heavy layouts, multiple links, marketing-style buttons, bulk-send formatting, and bright branded headers. The more your cold email looks like a campaign, the more confidently Gmail tabs it as one.
Plain-text-style email sidesteps the trigger. With no banner, no button grid, and minimal markup, there's little for the categorizer to latch onto — so the message has a far better shot at the primary inbox, which is the only inbox that converts in cold outreach.
Do images, links, and tracking pixels hurt deliverability?
Short answer: in cold outreach, yes — each one is a small risk with little upside. Spam filters weigh signals, and the most reliably human-looking email is the one that gives them nothing to flag.
Images are the worst offender. A heavy image-to-text ratio is a classic spam pattern, hosted images can fail to load and break trust, and a single image with barely any text is one of the loudest 'this is a marketing blast' signals there is. Links matter too: multiple links, shortened URLs, and mismatched display text all raise suspicion, and stacking several in a cold email reads like a campaign. Tracking pixels are the quiet one — that invisible open-tracking image is itself a flagged pattern, and recipients increasingly have it blocked anyway, so you pay the deliverability cost for data you don't even reliably get.
- Images — high image-to-text ratio is a spam signal; an image-only email is the loudest one. Keep cold email image-free.
- Links — one clear link beats five. Avoid URL shorteners and mismatched anchor text.
- Tracking pixels — flagged as a pattern, frequently blocked by recipients, and not worth the deliverability hit on a cold send.
- Heavy HTML wrappers — the markup the recipient never sees still gets read by the filter. Less code, fewer flags.
Light formatting: plain text doesn't mean ugly
Plain-text-style does not mean a wall of unbroken type. The goal is a message that reads like a thoughtful person wrote it quickly — and thoughtful people still hit Enter. The formatting that's safe is the formatting a human uses by reflex when typing, not the formatting a designer adds in a template builder.
Use short paragraphs — two or three lines each — with white space between them so the eye can move. Lead with one clear thought, make one ask, and sign off like a person. Skip the banner, the button, the columns, and the brand palette. If a merchant glanced at it on their phone, it should look like a note, not a brochure.
- Short paragraphs and line breaks — the way anyone naturally types a quick message.
- One link at most, shown as a plain URL or honest anchor text.
- A real-sounding subject line, lowercase or sentence case — not ALL CAPS or emoji-stuffed.
- A simple human sign-off. No logo, no social-icon footer, no graphics.
The 'note from a CEO's iPhone' principle
Here's the mental model we build every cold email around at MCA Rocket: write it like a busy founder firing off a quick message from their phone between meetings. No logo, no graphics, no design — just a few honest lines and a soft question. That single constraint solves the format problem, the deliverability problem, and the tone problem all at once.
It surprises people that our website is the exact opposite — lush, animated, the luxury storefront. That's deliberate. The website is where you build perceived value and earn trust at a glance. The cold email is where you earn a reply, and replies come from feeling personally addressed, not impressed by a template. Different jobs, different formats. The storefront should dazzle; the cold note should disappear into the inbox like it belongs there.
MCA is the most spam-complained-about industry online, so the margin for error in the cold inbox is thin. Plain-text-style email — paired with the warmed domains, rotating inboxes, and 100% unique copy that make it land at scale — is how cold MCA outreach reaches the primary inbox instead of the Promotions tab. The plain note isn't a lack of design. It's the design.
