Using dynamic content in email marketing campaigns

Most "dynamic content" in email is decided before the email leaves your platform. The ESP looks at a subscriber's segment, picks a block, and locks it in. By the time the email is opened, sometimes days later, that content is a snapshot of the past.

Using dynamic content in email marketing campaigns well means knowing which kind you're using and when. There are two kinds, they solve different problems, and the best campaigns use both.

Send-time dynamic content

This is what most ESPs mean by dynamic content. Conditional blocks, merge tags, and "show this section if" rules. Your platform evaluates them for each subscriber when the campaign is sent, and the result is fixed.

It's great for things that don't change after sending: a subscriber's name, their segment, their membership tier, the products you've chosen for their category. It's how you send one campaign that reads differently for new customers and loyal ones.

The limit is timing. Anything that could change between sending and opening, such as prices, stock, time left in a sale, or the weather, goes stale.

Open-time dynamic content

Open-time content is generated when the subscriber actually opens the email. It works through images: your email contains an image tag, and when it's opened, a service like Alterable draws the image with whatever is true at that moment.

That covers a lot of ground. A countdown shows the real time left. A product block shows what's in stock and at what price now. A map shows the nearest open store. A banner changes with the local weather. And because it's rendered per subscriber, it can also carry personal data like names and points balances into the artwork itself.

The email you sent Tuesday is still correct when it's opened on Friday. That's the whole idea.

Which campaigns benefit most

Promotions and flash sales

Countdown timers are the most common open-time content for a reason. A live deadline turns "ends soon" into something the reader can see. And when the sale ends, the timer can switch to an "offer ended" message, so late openers aren't promised something that's gone.

Abandoned cart and browse abandonment

Send-time content can include the product someone left behind. Open-time content can show it with the current price and stock level, and add a countdown if you're holding a discount. That's more persuasive and more honest.

Loyalty and rewards

Points balances change. A balance frozen at send time can be wrong by the time it's read. Rendering it at open, inside a designed hero image, makes the email feel like a personal statement rather than a newsletter.

Local and in-store campaigns

For brands with physical locations, a map to the nearest store, with distance and opening hours, turns interest into a visit. With open-time rendering, one image tag produces a different map for every subscriber.

Transactional updates

Order status, delivery tracking, event details. An image that re-renders on every open means customers can reopen the same email for the latest status instead of hunting for a new one.

Feedback

A one-click rating in the email itself (stars, numbers, or emoji faces) gets far more answers than a survey link. Results arrive while the campaign is still landing.

Combining both kinds

The strongest campaigns layer them. Send-time logic decides who gets which message: new customers see a welcome offer, loyal customers see an early-access note. Open-time content makes each message current: the offer comes with a live countdown, the product grid reflects stock, the hero shows their own points.

In practice, that means building your segments and conditional blocks in your ESP as usual, then adding open-time images into those blocks. Alterable's images are just image tags, so they drop into conditional sections without any special handling.

Setting it up with Alterable

Alterable covers the open-time side in one platform: countdown timers, personalized images, dynamic product blocks, store maps, surveys, and scratch cards. You build each piece in a browser, copy one image tag, and paste it into an HTML block in Klaviyo, Mailchimp, HubSpot, Brevo, or any other ESP.

Rules let an image change by location, device, language, time of day, or weather, with fallbacks for missing data. The free plan includes every content type with 10,000 impressions a month and no watermark, so you can try it on a real campaign before spending anything.

Mistakes that undo the benefit

Missing fallbacks are the most common. If your image assumes every subscriber has a city on file, the ones who don't will see something odd. Always set defaults.

Relying only on location detected at open is the second. Apple Mail and Gmail load images through their own servers, which can hide where a reader really is. Pass the location you already store in your ESP whenever you can, and treat open-time detection as a bonus.

The third is hiding everything in images. Keep your core message and call to action as live text and real buttons, so the email still works if images are blocked, and so screen readers and spam filters can read it.

Measuring whether it worked

Test one change at a time. Run your usual campaign against a version with one piece of open-time content, like a live timer or a personalized hero, and compare click-through rates. Opens are unreliable these days, so judge on clicks and conversions.

If you want to see the difference in your own campaign, start with the email that matters most this month. Build its dynamic piece on Alterable's free plan at alterable.com and send the two versions side by side.