Create a Spreadsheet in LibreOffice Calc

Before doing anything, you need to set up a spreadsheet with the information that you want to plug in to the mail merge. LibreOffice Calc is an excellent spreadsheet program that you can use to easily organize the information for your messages. Use the spreadsheet to organize specific personal details for each email, like recipient names and email addresses.

You can set up the spreadsheet like you would any other. Create column headings that will correspond to the variables that you’ll plug into your email. Then fill in the data below to match each column. When you’re done, go to “File,” then “Save As.” A save window will open up. At the bottom-left you’ll find a drop-down menu with file format options. Open it and scroll down until you find “Text CSV(.csv).” Select that one. It’s the format that Thunderbird accepts.

Get the Mail Merge Add-on

Open Thunderbird if you haven’t already. Open the menu in the top-right. Click on “Add-ons.” On the left menu click “Extensions.” That window will have a search bar to the right of the screen. Search for “Mail Merge.” The name of the add-on is “Mail Merge.” It will probably be the top result. Install it. Thunderbird will require a restart for the mail merge add-on to take effect. Do that if you need to.

Write Your Email

When Thunderbird starts back up, you’ll be able to use the Mail Merge. Start by writing your email the way you normally would.

Mail Merge uses variables. They look something like this: “{{Email}}.” Everywhere that you want to plug in the information from your spreadsheet, place these variables. Make sure that the words inside the brackets match the column headings that you set up in the spreadsheet. When you’re done writing your email, go to “File” in the email window and select “Mail Merge.”

A window will open up. Set the “Source” to CSV, then browse for the CSV file that you saved from LibreOffice Calc. You can leave everything else the same. It’s probably a good idea to send the messages later. Thunderbird will create the messages and place them in your outbox. You can check them for errors before sending them out. Otherwise, just send them immediately. That’s it! If you’ve been following along, you just sent your first mail merge from Thunderbird.