What makes a good CTA in email?

A good CTA tells the reader exactly what happens next, and gives them a reason to want it. That is it. The fluff around it (color theory, button shadows, "psychology of red") matters far less than getting those two things right.

Start with the verb. "Start your 14-day trial" beats "Click here" because the reader can picture the outcome before they tap. "Get the deliverability checklist" beats "Learn more" for the same reason. Vague labels make the reader stop and think, and a thinking reader is a closing-the-tab reader. Action plus payoff, in that order.

Pick one CTA per email. The whole point of the message is to push toward a single decision, so do not split that decision three ways with a primary button, a secondary button, and four text links to your latest blog posts. If you have three offers, you have three emails. If you really need a secondary action, make it a low-key text link well below the main button, not a competing button in the same color.

Make it a button, not a link buried in a paragraph. Buttons get seen, links get missed, especially on phones where readers skim with their thumbs. For the button itself, the WCAG 2.2 Target Size criterion sets a minimum tap target of 24 by 24 CSS pixels, and Apple's Human Interface Guidelines push that to 44 by 44 points for comfortable thumb use. In practice, that means roughly 44 to 50 pixels tall with real padding around the text. Anything smaller and people miss it or tap the wrong thing.

Contrast matters more than the specific color you pick. The button has to pop against the surrounding email, full stop. Whether that is bright orange, navy, or your brand green, the rule is the same: it should be the most obviously clickable thing on the screen. Run the email through a contrast checker if you are unsure. A pale button on a white background is invisible regardless of how clever the copy is.

About urgency: only use it when it is real. "Offer ends Friday" works if it actually ends Friday. "Limited time only" used on every email for a year teaches readers to ignore you. Manufactured pressure does not raise conversions in the long run, it just trains people to filter you out. Save urgency for genuine deadlines, restocks, or seat counts and it keeps its bite.

Test the wording, not just the color. The biggest CTA gains tend to come from rewriting the label, not changing the button from blue to green. Try a verb swap. Try adding the benefit ("Get your free audit" vs "Get the audit"). Try first-person ("Start my trial" sometimes beats "Start your trial"). See our note on content testing frameworks for how to run those tests without trashing your engagement metrics in the process.

Finally, the CTA does not live in isolation. The subject line sets the promise, the body backs it up, and the button delivers on it. If those three are out of sync (urgent subject, casual body, soft CTA), readers feel the seam and click less. Match the tone across the whole email and the CTA does most of its work before anyone reads the button text.