What a mail merge does and why you might use it

A mail merge takes one email template and sends it to a list of people, filling in each person's name, address, or other details automatically. Instead of writing "Dear Sarah" fifty times and copying the same message fifty times, you write it once and the mail merge inserts each person's information where you mark it.

The most common reason to use mail merge is to send a message that feels personal without doing the personalization by hand. You might send a reminder to a group of volunteers with each person's assigned shift, or notify customers about an account change with their specific account number included. The recipient sees their own name and details, not a generic "Dear Customer."

Mail merge works in Microsoft Outlook (the email program, not the web version), and in Gmail through a third-party tool. The steps differ between them, and the tool you use depends on which email program you already have.

Key Takeaways

  • A mail merge pulls names and details from a spreadsheet and inserts them into an email template, so each recipient sees their own information.
  • In Outlook, you create the email template first, then link it to a spreadsheet with the recipient list and the details to insert.
  • Gmail does not have built-in mail merge, but free tools like Mail Merge for Gmail or Mailmodo can do it by connecting your Gmail account to a spreadsheet.
  • The spreadsheet must have column headers that match exactly what you type in the email template, or the merge will not work.
  • Always send a test merge to yourself first to check that names and details appear in the right places before sending to your full list.

Setting up mail merge in Microsoft Outlook

Open Outlook and create a new email. Write the subject line and the body of the message as you normally would. Wherever you want a person's name, account number, or other detail to appear, you will mark that spot with a placeholder — Outlook calls this a "merge field."

To insert a merge field, click the Mailings tab at the top of the window. (If you do not see it, you may be in the web version of Outlook — mail merge only works in the desktop version.) Click Select Recipients, then choose Use an Existing List. Navigate to your spreadsheet file — it can be an Excel file, a CSV file, or an Access database. Select it and click Open.

Now go back to your email and position your cursor where you want the first piece of information to appear. Click Insert Merge Field and select the column header from your spreadsheet that matches what you want there. If your spreadsheet has a column called "FirstName", click that. Outlook will insert <<FirstName>> into your email. Repeat for each piece of information you want to merge.

Once all your merge fields are in place, click Finish & Merge, then Send Messages. Outlook will create a separate email for each row in your spreadsheet, fill in the merge fields, and send them all.

Setting up mail merge in Gmail with a third-party tool

Gmail's web interface does not have a built-in mail merge feature. Instead, you use a free add-on that connects Gmail to a spreadsheet. The two most widely used are Mail Merge for Gmail (made by Google) and Mailmodo. Both work the same way: they read your spreadsheet, create individual emails from your template, and send them through your Gmail account.

To use Mail Merge for Gmail, open Gmail and click the Google Apps menu (the grid of nine dots in the top right). Click More, then search for "Mail Merge for Gmail" and install it. Once installed, open a new email in Gmail and write your template. Click the Mail Merge for Gmail icon (it looks like an envelope with a plus sign) in the toolbar at the bottom of the compose window. A sidebar will open asking you to select a Google Sheet with your recipient list.

In your Google Sheet, put each person's information in a row, with column headers in the first row. The headers must match exactly what you type in your email. If you write "Dear {{FirstName}}", your spreadsheet must have a column called "FirstName" with no extra spaces. Click Next in the Mail Merge sidebar, review the preview, and click Send.

Preparing your spreadsheet so the merge works

The spreadsheet is where everything starts. Each row is one person. Each column is one piece of information — FirstName, LastName, Email, AccountNumber, or whatever you need. The column headers (the names in the first row) must match exactly what you type in your email template, including capitalization and spacing.

If your template says "Dear {{firstname}}" but your column is called "FirstName", the merge will fail or leave the field blank. The safest approach is to write your column headers first, then copy them exactly when you create your merge fields in the email.

Make sure the Email column contains valid email addresses — one per cell, with no extra spaces before or after. If an email address has a typo, that person will not receive the message, and you may not know it happened. Review the list before you merge.

Testing before you send to everyone

Always send a test merge to yourself first. In Outlook, after you click Finish & Merge, choose Merge to New Message instead of Send Messages. This creates all the merged emails in your Drafts folder without sending them. Open the first one and check that the merge fields filled in correctly. Look for the right name in the greeting, the right account number in the body, and anything else that should have changed. If something is wrong, close the drafts without sending, fix the template or the spreadsheet, and try again.

In Gmail with Mail Merge for Gmail, the sidebar shows a preview of the first email before you send. Check it carefully. If the merge fields are blank or wrong, stop and fix the column headers in your spreadsheet.

Common mistakes that break the merge

The most common mistake is a mismatch between the column header name and the merge field name. If your spreadsheet says "First Name" (with a space) but you type {{FirstName}} (no space) in the email, they will not match and the field will stay blank. Copy and paste the header name directly into your template to avoid this.

Another mistake is including extra spaces or line breaks in the spreadsheet cells. If a cell says " Sarah " instead of "Sarah", the merge will insert the spaces too, and the greeting will look odd. Clean up your data before you merge.

A third mistake is forgetting to include the Email column in your spreadsheet, or putting email addresses in the wrong format. The mail merge tool needs a column it can read as the recipient list. Check that every row has a valid email address in the same column.

What happens after you send a mail merge

Once the merge sends, each recipient receives an individual email with their own information filled in. From their perspective, it looks like you wrote to them personally — they do not see any merge field markers or know that others received a similar message. The email comes from your account and can be replied to normally.

In Outlook, the sent emails appear in your Sent folder as individual messages, one per recipient. In Gmail, they also appear as individual sent messages. If you need to track whether someone opened the email or clicked a link, you will need a separate tool — mail merge itself does not include tracking.

Frequently Asked Questions

Can I use mail merge to send emails to people outside my organization?

Yes. Mail merge works with any email addresses in your spreadsheet, whether they are inside or outside your organization. The recipient does not need any special account or permission — they just receive a regular email.

What if I want to include an attachment in a mail merge email?

In Outlook, you can attach a file to the template before you merge, and every recipient will get the same attachment. If you need different attachments for different people, mail merge alone cannot do that — you would need a more advanced tool. In Gmail with Mail Merge for Gmail, attachments are not supported through the add-on.

Can I schedule a mail merge to send later instead of right now?

Outlook does not have a built-in delay for mail merge — it sends when ready when you click Send. Gmail's Mail Merge for Gmail also sends right away. If you need to send at a specific time, you can create the merged emails, save them as drafts, and send them manually at the time you want.

What if someone's name or email is missing from my spreadsheet?

The merge will skip that row or leave the field blank, depending on which information is missing. If the Email column is empty, that person will not receive anything. If a name field is empty, the greeting will say "Dear " with nothing after it. Review your spreadsheet for gaps before you merge.

Can I merge emails with different templates for different groups?

Not in a single merge. You would create separate templates and run separate merges — one for volunteers, one for customers, one for staff, each with its own spreadsheet and its own template. This takes more time but gives you control over what each group sees.