How to send personalised WhatsApp messages in bulk (mail merge guide)

Last updated: 12 October 2026

A mail merge is not a special feature you have to buy — it is just a spreadsheet with one column per value and a message with placeholders. This guide shows you exactly how to structure the sheet, how the placeholders resolve, the mistakes that break a merge, and how to preview every recipient's version before you send a single message. No API and no developer.

"Personalised" vs "spammy": the line that matters

The word personalisation gets used to mean two very different things, and only one of them helps you.

Real personalisation uses a fact you already hold about the recipient — their name, their company, an order reference, an appointment date — and places it where it improves the message. The recipient sees something true and specific, and the message reads as though a person wrote it for them.

Fake familiarity is when a message sounds personal but carries no real information: "Hi friend, I noticed you might be interested in…". Adding a first name to a message that is otherwise identical for five hundred strangers does not make it personal; it makes it a mailshot with a name slot.

Keep that table in mind as you build the merge. The mechanics below make messages accurate; they cannot make an audience willing.

How to structure your spreadsheet

The spreadsheet is the whole merge. Get it right and the sending is easy.

• Header row required. The first row holds your column names — name, phone, company, date. The importer treats this row as labels, and every placeholder is matched to a column name, so the header is not optional.
• One column per variable. Do not pack "Ava Thompson, Northwind Co" into a single cell. If you want to greet a person and mention their company, that is two columns and two placeholders.
• One column for the phone number, in international format. Country code first, then the subscriber number, with no national trunk prefix. Keep it in its own column so the tool knows where the numbers are.
• One row per recipient, no blank rows in the middle. A blank row is read as a contact with missing values, which is exactly the situation that produces a broken merge.
• Save as CSV UTF-8. A plain export can mangle accented names and other non-Latin characters. UTF-8 is the safe choice.

How placeholders work

A placeholder is a token in your message that stands in for a column value. Write one message, and at send time each token is replaced with that recipient's value from the matching column.

You are not limited to these three. Any column you add becomes a variable you can call on, so {week}, {dietary}, {trainer} or whatever your list actually tracks will all work, provided the column name matches the token. That is what turns a template into a custom message: the spreadsheet supplies every variable, and each recipient receives their own version at send time.

A worked example

Here is a small US-style demo list. The header row names the columns; each row is one recipient.

Write this template once:

Hi {name}, your delivery to {company} is booked for {date}. Reply here if you need to change it.

And each recipient receives their own version:

One template, three different messages, and every one of them is factually correct for that person. That is the entire value of a merge, and it takes a few minutes to set up. The same pattern scales to dozens or hundreds of rows. Note that the numbers above are stored with the leading + for readability; if your sending tool expects digits only, normalise the column to 12025550101 before importing.

What breaks a merge

Merge failures are almost always data problems, not tool problems. These are the ones that catch people out.

Preview the merge before you send

You would not print a hundred letters without checking one, and the message you are about to send hundreds of times deserves the same. The free WhatsApp Message Personaliser does exactly this one job: paste your template and a few sample rows and it shows you the finished message each person would receive. It is the cheapest possible way to catch an empty column, a mistyped placeholder or a number that is going to fail — before any message leaves your account.

Run the preview, fix anything that looks wrong, then import the same data into the sender and run a small test batch to your own number. Checking the merge is a two-minute habit that saves a very awkward follow-up email.

Writing the message so the merge reads naturally

The final step is the writing, and a good merge field can still be dropped in badly.

• Put the placeholder where it belongs grammatically. "Hi {name}," flows; a name jammed into the middle of a sentence often does not.
• Do not let the placeholder be the only variable content. If everything except the name is identical for hundreds of people, the sameness is still obvious. Add a genuinely specific detail where you have one.
• Plan for the fallback. Decide what should appear when a column is empty, so you never send "Hi ," to half your list.
• Keep it short and human. A WhatsApp message is read on a phone; two or three sentences that say one useful thing beat a wall of text.
• Skip the pressure. Phrases that manufacture urgency or read like an unsolicited advert are what provoke a report. Write the way you would message someone you know.

If you are still shaping the wording, our message templates guide covers structures that work for reminders, updates and follow-ups, and the bulk sending limits guide explains the pacing and consent habits that keep a personalised campaign on the right side of WhatsApp's rules.

Frequently asked questions