Merge tags: what they fill in, and the fallback that saves the greeting
A placeholder your email platform swaps for something it knows about each reader. First names are the famous one. The useful ones carry what someone actually did.
- 082Merge Tag
- A placeholder in email templates that is replaced with subscriber-specific information, like their name or location.
- Also called
- Personalisation tags, which is Klaviyo's name for them
- Looks like
- A field name in double curly brackets, with a fallback after it
- Never send without
- A fallback for anyone whose field is empty
How a merge tag works, and what Klaviyo calls one
When the email sends, the platform looks up a field on each person's profile and drops the value in. Mailchimp calls these merge tags. Klaviyo calls them personalisation tags, and used to call them template tags, so you'll hear all three in the same meeting.
In Klaviyo a first name greeting looks like this: Hi {{ first_name|title|default:'there' }}. The title part tidies the capitals. The default part is what anyone without a saved name sees, so they get Hi there, not a greeting with a hole in it.
The fallback is the whole job
A merge tag is only as good as the data behind it, and sign-up data is messy. Before anything sends, picture the worst profile on your list.
- No name saved and no fallback, so the greeting has a gap in it
- A name typed in capitals, or all in lower case
- Junk in the field: test, a full stop, an email address
- A tag with a typo, which won't pull the field you meant
Klaviyo's preview lets you see the email as a real profile, and in flows triggered by an event, as a recent example of that event. Preview it as someone with an empty name before it goes.
The merge tags worth more than a first name
A first name is manners. The tags that change what someone does carry what they did, or what they told you.
| The tag pulls in | Where it earns its keep |
|---|---|
| The product left in the basket | Cart and checkout reminders |
| Their points balance, if your loyalty app syncs it | Loyalty and winback emails |
| The size or skin type they told you | The welcome flow and product picks |
| The last thing they bought | Post-purchase and replenishment emails |
When you need to swap a whole block, not a word, that's dynamic content. And if you want more to work with than a name, ask for it: zero-party data is the honest way to get it.
Related terms
FAQs
Is a merge tag the same as dynamic content?
Related, not the same. A merge tag swaps a single value into a sentence: a name, a product, a points balance. Dynamic content changes whole sections of the email depending on who's reading, like a block only VIPs see. Most good emails use both, and both need a fallback.
What happens if a subscriber has no first name saved?
Without a fallback, they get a greeting with a hole in it. With one, they get whatever you chose instead, like Hi there. Set a default on every tag, or write greetings that don't need a name at all, and check the email as a profile with an empty name before it sends.
Can I use merge tags in a subject line?
Yes. Klaviyo's personalisation tags work in subject lines, with the same fallback rules as the body. A missing value looks worse there than anywhere else, because it's the first thing anyone reads, so preview the subject as a profile with gaps before you send.
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