How to Send a Mail Merge in Mozilla Thunderbird

How to Send Mass Emails Using Mail Merge in Mozilla Thunderbird

One of the most annoying things that could happen is receiving an unsolicited email from someone which obviously shows it is a mass email. As a recipient you know and can tell if it is another marketing hype or a sincere message of “Hi, Hello, and Goodbye!”

If you’re a Google Apps user, perhaps you have heard the sending a mail merge in Gmail that allows you to send a single message to quite a number of recipients without looking spammy using Google Drive and Google Scripts. On the other hand, there is another way to do it using the Mail Merge extension in Mozilla Thunderbird. Create a message or template in the drafts and send it to many recipients, with it looking personal and customised.

Kicking it off with the basics and email configurations

This tutorial requires you to have the following:

Install Mozilla Thunderbird

For first time users, you need to set up your default email account in Thunderbird. Here are expanded tutorials on Automatic Account Configuration and Manual Account Configuration on Mozilla support.

How to set up Mail Merge and Thunderbird

If you’re using Thunderbird as your default e-mail client, proceed to the Mail Merge download and installation.

1. After downloading the Mail Merge file “mail_merge-3.10.1-sm+tb.xpi,” launch Thunderbird. You may set it as your default email client or skip the integration.

Set Thunderbird as default.

2. Click Tools and choose “Add-ons,” and it will direct you to the “Add-ons Manager” tab. See the gear icon adjacent the Search bar, and click the drop-down menu.

Thunderbird Add-ons Manager

3. Choose “Install Add-on from File,” and open the Mail Merge file that you previously downloaded; restart the email client for the changes to take effect.

Restart Thunderbird for the changes to take effect.

Prepare the contacts in a spreadsheet as CSV file

Mail Merge is beneficial for those who have been building their e-mail contacts in a spreadsheet. In this tutorial, here’s what it looks like.

1. Create a spreadsheet and save it as a .csv file (e.g. mtelist.csv based on screenshot) if you don’t have one.

Create a spreadsheet and save it as dot-csv file.

2. Make sure that the columns are filled up with names and email addresses. Choose “Save as” for the file and click OK. Never mind the warning in the dialog box; proceed to the next step.

Ignore the Compatibility check recommended warning.

Sending the first personalised message

1. Click the “Write text” icon and create a new message. You may also add more recipients manually in the “To” field.

2. When writing, always include the text you want to use from the CSV file you saved previously with double brackets, e.g. {{Name}}. See A1 on the spreadsheet above.

Include text from CSV file with double brackets.

3. Once you finish writing the draft, go to File and select Mail Merge. Set the Mail Source to CSV, the Delivery Mode (Send as Draft, Send Later, and Send Now), the Format (HTML or Plain) and if you have attachments.

Go to File and select Mail Merge.

4. Click Browse to upload the CSV file from the directory where you have saved it and click OK. Mail Merge will run, and it will send your message according to the Delivery Mode.

Final thoughts

You can check if the messages are sent in the Sent folder. If you have set the Delivery Mode as Send Later, then they will be automatically saved in Outbox under Local Folders. Keep in mind that the text inside the double brackets should be the same text or name of the column labeled in the CSV file you have saved. See A1 on the spreadsheet above. The CSV option works well; however, when I tried to do it via Address Book, I keep on getting errors.

Let us know how it works on your side and feel free to share other ways to create mail merge.

Maria Krisette Capati Maria Krisette Capati

Krisette is a technology writer who loves to cover disruptive technologies, trends, and a myriad of rumors and news updates. To satiate the inconsolable longing to feed her gadget addiction, she simply writes and tinker her gadgets for reviews. You may follow her blurbs, too! @krisettecapati


  1. Did not save the files in the draft folder. Put the original merge file into the templates folder.

  2. This does not work at all. Neither with address book nor CSV. One of 566 messages goes into the templates folder.
    Bloody useless.

  3. The mail merge seems to work fine if you are willing to accept its limitations.
    Set up your first draft with an arbitrary email address or your own.

    The explanation above is good except the referenced versions of Mail Merge and Thunderbird are old.

    Using Mail Merge Version 4.3.0 of 1/29/2016
    and Thunderbird version 38.4.0 on Ubuntu 14.04
    it merges information well from CSV but
    you have to work through each message draft to enter the correct email address in the To line.
    It is a good poor man’s version of mail merge – excellent for the price!


  4. I couldn’t get this to work with days of trying It’s a useless bugged mess.
    If there is a way for workind around all the flawas of this plugin, you reakky need to point out more detailed what one has to do, and what will make it fail.

  5. Do your recipients a favour and change the mail merge dialog from “Send now” to “Send later”.

    After processsing the mail, go to your Outbox and check the result. If you don’t like it, fine tune and repeat until you are satisfied.

    Then send your outbox.

    If done like that, in the above example, Maria would have noticed, that in the greeting the comma is in the wrong place and could have corrected that without bothering anybody.

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