Word mail merge: send 100 personalised emails in 10 minutes

You need to send the same letter to 80 customers, each with their own name, account number and recent balance. Without mail merge, that's 80 copy-paste operations and an hour of error-prone work. With mail merge, you build the letter once, point it at a spreadsheet, and Word personalises every copy automatically.

This guide walks through the full mail merge workflow — Excel list, Word document with merge fields, generating either printed letters or personalised emails — with the realistic gotchas built in.

What you'll need

• Microsoft Word (any modern version with mail merge — Word 365, 2021, 2019, 2016).
• Microsoft Excel with your recipient list, one row per recipient, column headers in row 1.
• For email merges, Outlook for Windows. Mail merge to email requires Outlook desktop — Outlook on the web alone won't work.

Step 1: Prepare the recipient list in Excel

A solid mail merge starts with a clean spreadsheet. Build a workbook with one sheet that looks like:

FirstName	LastName	Email	Company	Balance
Sarah	Khan	sarah@example.com	Acme Corp	1240.50
David	Lee	david@example.com	Globex	89.00
Maria	Ng	maria@example.com	Initech	2399.99

Rules:

• One row per recipient. No merged cells. No blank rows in the middle.
• Column headers on row 1. The headers become the merge field names later.
• Email column is required for email merges. Plain text addresses.
• Numbers like Balance should be formatted in Excel exactly as you want them to appear in Word — Word reads the underlying number, not the formatted display.

Save the workbook. Close it (some Word versions require the file to be closed during merge).

Step 2: Build the Word document with merge fields

1. Open Word, start a new document.
2. Go to the Mailings tab on the ribbon.
3. Click Start Mail Merge → Letters (or Email messages if you're sending emails — both are similar, we'll show Letters first).
4. Click Select Recipients → Use an Existing List.
5. Browse to your Excel file. Word asks which sheet to use; pick the right one and tick "First row of data contains column headers". OK.

Now your recipient list is linked. Word knows the columns but the document is empty of merge fields.

6. Type your letter. Where you want to insert a personalised value, click Insert Merge Field on the Mailings ribbon and pick the column. For example:

Dear «FirstName»,

Your current balance with «Company» is £«Balance». Please contact us if you have questions.

Best regards, Lina

The «FirstName», «Company», «Balance» chunks are merge fields — placeholders Word will replace with each recipient's actual data.

Step 3: Preview each personalised letter

Before generating all the merged letters, preview:

1. Click Preview Results on the Mailings ribbon.
2. Word shows the letter for the first recipient with their values filled in.
3. Use the arrow buttons next to Preview Results to cycle through each recipient. Spot-check 5–10 to catch typos and bad data.

If a value looks wrong (like 1240.5 showing as 1240.5 instead of 1240.50), see "Number formatting" below.

Step 4a: Print or PDF the letters

When previews look good:

1. Finish & Merge → Print Documents to print all letters in sequence.
2. Or Finish & Merge → Edit Individual Documents → All to generate a new Word document containing all letters concatenated. From there you can print, save as PDF, or review further.

The "Edit Individual Documents" route is safer for the first time — you see the actual output before paper is wasted.

Step 4b: Send personalised emails

For email merges, the steps are similar but with one important caveat: Outlook for Windows must be open and connected.

1. Set up the document the same way as a letter merge, but click Start Mail Merge → E-mail Messages instead.
2. Make sure your Excel sheet has an Email column (Word needs to know where to send each message).
3. Build the document with merge fields just like before.
4. When ready, Finish & Merge → Send Email Messages.
5. In the dialog:
   • To: pick the Email column.
   • Subject: type the subject line (no merge fields here unless you use a workaround).
   • Mail format: HTML if your letter has images or formatting.
   • Records: All to send to everyone, or a range.
6. Click OK.

Word silently hands each personalised message to Outlook, which sends them through your usual mail account. Outlook's Sent Items will show each individual message.

Limitations of email mail merge

Word's built-in email merge is fine for simple announcements but has limits:

• Subject lines can't contain merge fields without a manual workaround.
• No tracking of opens or clicks (use a marketing platform for that).
• One sender, one mail provider. You can't merge from multiple accounts in one batch.
• No A/B testing or scheduled send.
• Rate limits — Microsoft 365 limits outgoing mail to roughly 10,000 recipients per day. For a 100-recipient merge you'll be fine; for 10,000+ recipients you may need to space the batches.

For higher-end marketing, use Mailchimp, ConvertKit, Microsoft Customer Voice, or similar. Word mail merge is best for transactional letters and modest internal communications.

Number and date formatting tricks

Excel's display format is not transferred to Word — Word reads the raw underlying number or date. To get £1,240.50 instead of 1240.5:

1. In your Word document, right-click the «Balance» merge field and choose Edit Field.
2. The field code looks like { MERGEFIELD "Balance" }.
3. Change it to { MERGEFIELD "Balance" \# "£#,##0.00" }.
4. Press F9 to update the field display.

The slash-hash code is a numeric picture switch. For dates, the switch is \@: { MERGEFIELD "DueDate" \@ "d MMMM yyyy" } displays as "9 May 2026".

Common problems

• Recipient list shows 0 records. Almost always means the Excel sheet has blank rows or headers in the wrong row. Check the data.
• The merge field shows «FirstName» instead of the name. You're seeing the field code. Click Preview Results to see real data.
• Outlook stays open after merge with all messages in Outbox. Some Outlook configurations don't send mail merge messages automatically. Click Send/Receive in Outlook to push them out.
• Word can't find the data source. If you move or rename the Excel file, you need to re-link via Mailings → Select Recipients.

Test before sending

Before pressing Send on a 200-recipient email merge, do this:

1. In your Excel data, add yourself as the first row.
2. Run the merge but limit it to the first record only (the dialog has a Records option).
3. Check the message arrives looking right, with proper formatting, in your own inbox.
4. Then run the full merge.

Five extra minutes here saves a recall situation later.

TL;DR

Mail merge personalises a single Word document for many recipients using data from an Excel sheet. Build a clean spreadsheet (one row per recipient, no merged cells), link it via Mailings → Select Recipients, insert merge fields, preview, then choose Print, Edit Individual Documents, or Send Email Messages. Use numeric picture switches like \# "£#,##0.00" to format numbers, and always test with a single record before running the full batch.