Mail Merge is an experimental Thunderbird add-on that increases the email client’s mass mailing capabilities. It does so by introducing two new options to the email software: Mass Mail and Personal Mail.

Mass Mail

Mass Mail is ingenious. The user writing the email starts by writing one email that should be send out to all recipients. This includes the title, body and possible attachments. Then all recipients are added to that email in the appropriate fields. A click on the Mass Mail button (available under File > Mass Mail) will now create individual emails for each email recipient and put them in the outbox of the email client. Each recipient will therefor get an individual email message so that no other email addresses appear in the mail header.

Personal Mail

One problem of the Mass Mail approach is that the emails cannot address the individual. Adding Hej Frank to a mass mail would send that greeting to all other recipients as well. That’s where Personal Mail comes into play. Personal Mail makes use of variables and csv files to address individuals in mass mailings. Variables can be added to any field in the email in the form {{Variable}}. It is for instance possible to write an email like the following:

To: {{Mail}}
Subject: {{ID}}: Notification
Body: Hi {{Name}}, this email …

The selection of File > Personal Mail after writing the email will open a dialog with the mandatory option to load a csv file containing the information. The developer does not describe how the csv should look like and I was not able to figure it out on my own. Users who would like to make use of that feature might want to contact the developer directly. The email address is published at the Mozilla Thunderbird page of the add-on. Mail Merge is compatible with both Thunderbird 2 and 3 and can be downloaded from the official Mozilla website.