Most ecommerce popups are built backwards. They ask for an email, promise a discount, and then send the shopper off to their inbox to go find it. Half of those people never come back. The email lands in promotions, or they were browsing on their phone between other things, and the moment passes. The store gets a subscriber and loses a sale. The usual advice is to tweak the headline or test a different percentage. The real fix is structural.
The version that works has three parts, and none of them are complicated.
First, show the code on the screen, right away, the second the email goes in. Do not make the reward live in the inbox. The email is a backup, not the delivery mechanism. Klaviyo supports unique codes on the success step natively, and it can apply the code at checkout automatically, so the shopper does not even have to copy anything. The offer should be usable within the same tab they are already in.
Second, give the code a real expiry and show a countdown next to it. Forty eight hours is a good default. Long enough that nobody feels pressured, short enough that it does not become a coupon that lives in a notes app forever. The countdown is what turns a nice gesture into a reason to finish the order today. One honest caveat: the timer in the popup resets if the page reloads, so the timer that actually governs the deadline should live in the welcome email, where it is tied to the person rather than the session.
Third, make sure the offer does not collide with anything you already run. If the store has a subscribe and save discount, decide up front whether the welcome code stacks with it, and say so in the popup. Ambiguity at checkout is where these things quietly die.
On timing, the two triggers worth using are a short delay of roughly ten to fifteen seconds and exit intent, which works on mobile as well as desktop now. Show it once. If someone dismisses it, collapse it into a small tab at the edge of the screen instead of reopening it on the next page. People who want the offer will find the tab. People who do not will thank you for not asking again.
We have found that a quiz style popup, three quick questions that route someone to the right product before the email field appears, outperforms a plain offer on product pages where people are still deciding. On the homepage, the plain offer wins. Build both, put each where it belongs, and let the numbers settle it.
This is how we approach email capture at Burgama. The popup is not the goal. The order that follows it is.