4 easy steps to mail merge with Thunderbird

1. Install Mail Merge add-on to Thunderbird.

2. Create E-mail Contact List in MS Excel as shown below and save it as CSV (Comma delimited).

3. Create a new message for Thunderbird file menu and enter {{email}} instated of  email ID in "to" field and  "{{firstname}} {{lastname}} , " instated firstname and lastname of the receiver person.

4. After completing the 3rd step just click Mail Merge option for file menu after a dialog box is open, select source as CSV, Deliver mode as [Send later, Send now, Save As Draft] I selected Save as Draft, Format as [plain text, HTML, Both] I select Both and keep remain all default as shown in above image and click OK button and it result as follows.

Enjoy :)

Source: https://addons.mozilla.org/en-US/thunderbird/addon/mail-merge/