What is mail merge?

How mail merge works

Mail merge requires two components: a template and a data source.

• Template: A single message containing merge fields (also called merge tags or placeholders), such as {{name}} or {{company}}.
• Data source: A spreadsheet, CSV file, or database containing your recipient information. Each row represents one recipient; each column is a field (name, email, company, etc.).

When you run a mail merge, the software reads each row, replaces the merge fields with real data, and generates a personalised email or document for each recipient. In Gmail, each message is sent individually with the recipient's details inserted.

Real examples of mail merge

Example 1: Recruitment outreach

Template:

Hi {{name}},

I noticed your background in {{skill}} and thought you might be interested in our {{role}} opening at {{company}}.

Would you be free for a quick call next week?

Best,
Jamie

Data source (CSV):

Result: Two personalised emails, one to Alex about React and one to Jordan about Python.

Example 2: Event invitations

A charity sends invitations to supporters, personalising the salutation and mentioning each person's previous donation amount.

Example 3: Invoice reminders

A freelancer emails clients with unpaid invoices, inserting the client name, invoice number, and outstanding balance into a polite reminder.

Mail merge in Word, Gmail, and Google Sheets

Microsoft Word

Word's built-in mail merge creates printed letters, envelopes, or labels. It pulls data from Excel or Outlook contacts and generates a single merged document. It does not send emails directly unless you use Outlook integration.

Gmail and Google Sheets

Gmail has no native mail merge feature. To send personalised bulk emails from Gmail, you need a third-party tool or add-on that connects to Google Sheets. These tools read your spreadsheet, insert data into your email template, and send each message from your Gmail account individually.

Why use Gmail mail merge? You send from your own address, maintaining your domain and sender reputation. Recipients see a personal email, not a mass mailing. Every message can be previewed before sending.

Google Sheets add-ons vs dedicated tools

Google Sheets add-ons run inside your spreadsheet and require manual setup each time. Dedicated mail merge tools (like MailMerge) offer a dashboard, template library, preview mode, and campaign tracking.

Common mail merge mistakes

• Missing merge fields: Forgetting to include {{name}} or misspelling the field name, resulting in blank or broken text.
• Incorrect data formatting: Dates, currency, or names formatted inconsistently in the spreadsheet.
• Not testing first: Sending to all recipients without a test run. Always send a test email to yourself.
• Ignoring Gmail sending limits: Gmail restricts sending to 500 recipients per day (personal) or 2,000 (Google Workspace). Mail merge does not bypass this limit.
• Using the wrong column: Mapping the wrong data column to a merge field, such as putting a company name where a person's name should be.

When to use mail merge

Mail merge is ideal when you need to:

• Send personalised introductions, follow-ups, or invitations to a list of contacts.
• Maintain your own email address and avoid generic "noreply@" sender addresses.
• Preview and approve every message before it goes out.
• Stay within Gmail's sending limits (under 500 or 2,000 emails per day).
• Comply with UK GDPR and PECR by keeping email data transparent and under your control.

When not to use mail merge: If you need advanced analytics, A/B testing, or you're sending tens of thousands of emails, a dedicated email marketing platform (such as Mailchimp or SendGrid) may be more appropriate.

Related guides

• How to do a mail merge in Gmail (step-by-step)
• Mail merge from Google Sheets to Gmail
• Gmail sending limits explained
• UK GDPR and PECR for bulk email