How to Do a Mail Merge in Word for Letters and Emails

Mail merge is how one letter becomes a hundred personal ones. You write the message once, connect a list of names and addresses, and Word fills in each person's details. I've seen small businesses use it for client thank-you letters, event invitations, certificates and personalised follow-ups that would take a whole afternoon to type by hand.

It has a reputation for being complicated, mostly because there are three moving parts. Once you see how they fit, it's a calm, logical process. Here's the full walkthrough for letters, plus the email version and its limits.

The three parts of a Word mail merge

Part	Its job
Main document	The letter or email you write once, with gaps for personal details
Data source	Your list of recipients, most often an Excel sheet or Outlook contacts
Merge fields	Placeholders such as first name or address that pull from the list

Microsoft says Excel spreadsheets and Outlook contact lists are the most common data sources. On a Mac you can also create a Word data file on the spot if you don't have a list yet.

Getting your Excel list ready for a mail merge

Most merge headaches start in the spreadsheet, so spend five minutes here first.

• Keep all the recipients on one sheet, with a clear heading at the top of each column, such as First name, Company and Postcode.
• Format postcode and ZIP code columns as text. Microsoft warns that leading zeros are lost in a merge otherwise.
• Format any column holding a percentage as text too, because Microsoft notes the percentage format changes the value Word picks up.
• Save the spreadsheet with a new file name before you connect it.
• When Word asks, tick My data has headers so it uses your column names as field names.

Starting a letter mail merge in Word

1. Open a blank document and go to Mailings.
2. Select Start Mail Merge, then Letters.
3. Type the body of your letter, leaving out the parts that change for each person.
4. Open Select Recipients and choose your list, such as your saved Excel file.

If you only want some people from the list, the recipient list can be sorted and filtered before you merge, so you can leave out anyone who shouldn't get this letter.

Adding personal details with Word merge fields

Now click where each personal detail should go and insert a field.

1. For a full postal address, select Address Block, pick a name format and select OK.
2. For the opening line, select Greeting Line, choose a format such as Dear followed by the first name, and select OK.
3. For anything else, such as a company name, use Insert Merge Field and pick the column you want. On a Mac, Microsoft says to select each field and choose OK.

Fields show as names inside angled brackets. Don't type those brackets yourself, because Word won't recognise them as fields.

Checking every letter with Preview Results

Before anything prints, go to Mailings and select Preview Results. Word swaps the fields for real details from the first record. Use the Next and Previous record buttons to step through a few, looking for blank greetings, odd spacing or addresses in the wrong order. Select Preview Results again to switch back to the field view.

This is the step I'd never skip. A letter addressed to Dear First Name damages trust much faster than a slightly late one.

Finishing a Word mail merge

Go to Finish & Merge and pick what you want Word to do:

• Edit Individual Documents creates one long document with every letter, so you can tweak any of them before printing.
• Print Documents sends them straight to the printer.
• Send Email Messages (Windows only) turns the merge into individual emails.

Then save the main document. Microsoft says it stays linked to your list, and next time you open it Word asks whether to keep the connection. Choose Yes to reuse the same setup.

Running an email mail merge from Word

For personalised emails, start with Mailings, Start Mail Merge, E-mail Messages, then select your recipients. When you're ready, choose Finish & Merge, Send E-mail Messages, pick the email address column in the To box, type a Subject line and choose HTML or Plain text. Microsoft says you'll need a MAPI-compatible email program such as Outlook or Gmail installed.

Know the limits before you rely on it. Microsoft says each person's address is the only one on the To line, you can't CC or BCC anyone and you can't add attachments, although links are fine. I'd also send a test to yourself first, and keep the list small if you're sending from an ordinary mailbox rather than a dedicated email tool.

Mail merge in Word for the web

Microsoft says you can't perform a mail merge or change merge settings in Word for the web. A merge document made in the desktop app keeps its settings when opened in the browser, but you'll need the desktop app to run it.

Writing a mail merge letter people want to read

Personal fields get the letter opened, but the words do the rest. Keep it short, lead with what's in it for the reader and end with one clear next step. If you're new to persuasive writing, my beginner's path into copywriting covers the basics. And for a team sending letters on behalf of one business, agree a tone first with a short brand voice document everyone can follow.

Frequently asked questions

What do I need to do a mail merge in Word?

A main document written in Word and a list of recipients. Microsoft says Excel spreadsheets and Outlook contact lists are the most common sources.

Why are the leading zeros missing from my postcodes after a merge?

The column wasn't formatted as text. Microsoft says postcodes and ZIP codes need text formatting to keep their data during a merge.

Can I attach a file to a mail merge email from Word?

No. Microsoft says you can't add attachments or CC and BCC recipients in a Word email merge, though you can include links.

Can I do a mail merge in Word for the web?

No. Microsoft says Word for the web can't perform a mail merge or edit merge settings, so use the desktop app.

How do I check the merge before printing?

Select Preview Results on the Mailings tab and use the Next and Previous record buttons to look through several letters.