This procedure explains how to create multiple, customized e-mail messages using data in a spreadsheet.
The only Thunderbird extension that I could find to do mail merge from an external file was mailtweak. It has many other functions as well that aren't needed but they can be disabled. All of this should be done as the user who wants to send the mail; no administrator privileges are required.
- In a web browser, go to the mailtweak installation page and find the download link on the page.
- Start Thunderbird and choose Tools, Add-ons from the menu bar.
- Drag the download link from the Firefox window to the Thunderbird extensions dialog. The extension should install. Restart Thunderbird.
- The first time Thunderbird runs with the new extension, you get a configuration dialog. Enable the Personlize messages tweak and disable all others. If you don't do this, there won't be a Personalize menu option when you look for it in Thunderbird below.
- Restart Thunderbird.
Now the extension is set, and the user can do a mail merge message any time.
Creating custom messages
The mailtweak extension has online documentation if you want more detail than is here.
- Start with a spreadsheet with the data you want in the
message, including the e-mail address. Make sure there
is a header row with names for all columns; these names
must not contain spaces. According to the documentation,
mailtweak will use the first column whose data has an
@as the e-mail address; I guess its header value doesn't matter.
- Save the spreadsheet as CSV.
- In Thunderbird, choose Message, Personalize. Leave the
To: empty, fill in the subject and message body. When you
want to use a value from the data file, surround its name
%%firstname%%. This field name is case-sensitive, i.e., firstname won't work if the csv file has FirstName.
- When your (template) message is all ready, click the Personalize button. You'll get a File open dialog to select your saved CSV file.
- If you have Thunderbird set to check spelling before sending, you may get the spell check dialog now. When you're done, click Send on that dialog.
- This next dialog is important! You'll be asked whether to send the messages now. Choose Leave unsent. The messages will be deposited in the Unsent folder under Local Folders.
- Review the messages and make sure they look correct. Also make sure that there are no other messages in the Unsent folder that you don't want to send. Then right-click on the Unsent folder and choose Send Unsent Messages; it will send all messages in the Unsent folder.