If I understand your question correctly, it sounds like you want to do a mail merge. To do this in Thunderbird, you need to install the [https://addons.mozilla.org/en-us/thunderbird/addon/mail-merge/ Mail Merge extension]. Regarding copying the Excel list into Thunderbird, you need to save it as a CSV file. According to [https://addons.mozilla.org/en-us/thunderbird/addon/mail-merge/reviews/680428/ a review on the add-on's home page], it's important to select the option "MS-DOS Comma Separated (.csv)" from the file dialog. To import the list of addresses into Thunderbird, you should then be able to follow the Step by Step (CSV) instructions given in the "About this Add-on" section on the add-on's home page.

Thanks for the response. I am an 85 year old novice and may not have made my problem as explicit as I should have. My first issue is how do I get the excel file copied into a functional address list within Thunderbird. I now understand that a coma, CSV file is needed ...... Now what do I do with it and Thunderbird to combine them? Thanks again Jim

No problem, we're glad to help. If you've exported the Excel list as a CSV file, the next step is to install the Mail Merge extension in Thunderbird. You can do that by opening the Add-ons Manager (Tools->Add-ons), and clicking on Mail Merge in the list of featured add-ons. Click on the button that says "+ Add to Thunderbird" and restart Thunderbird after the add-on has installed. Once you've installed the extension, follow these instructions (which I've copied from [https://addons.mozilla.org/en-us/thunderbird/addon/mail-merge/ the add-on's home page]): <blockquote cite="https://addons.mozilla.org/en-us/thunderbird/addon/mail-merge/"> '''Step by Step:''' (CSV)<br>Screenshots: [http://outgoing.mozilla.org/v1/ce942752306c373d3e91a61eec8e51c4fe92faa60529a3b6be3a8df61f643903/https%3A//addons.cdn.mozilla.net/img/uploads/previews/full/82/82712.png Draft Message] | [http://outgoing.mozilla.org/v1/2ccabe4e5a9248d5c722eab17f9e6b306e230ad17f0809719a8d75f1721abb35/https%3A//addons.cdn.mozilla.net/img/uploads/previews/full/82/82714.png Draft Message] | [http://outgoing.mozilla.org/v1/8c3aea70f62cf35ba9653d052a9613b7230ad14705fc3af8324023f601567220/https%3A//addons.cdn.mozilla.net/img/uploads/previews/full/82/82708.png Mail Merge Dialog]<br><ol><li>Create a New Message ("File -&gt; New -&gt; Message")</li><li>Add the Variable(s) to To, e.g.: <em>{{Email}}</em> or <em>{{FirstName}} {{LastName}} &lt;{{Email}}&gt;</em></li><li>Add the Recipients to Cc (optional) (variables are supported)</li><li>Add the Recipients to Bcc (optional) (variables are supported)</li><li>Add the Subject (variables are supported)</li><li>Add the Body (variables are supported)</li><li>Add the Attachments (optional)</li><li>Click "File -&gt; Mail Merge"</li><li>Select "CSV" and check "Deliver Mode" and "Format"</li><li>Add (individual) Attachments (optional) (variables are supported)</li><li>Select "Filename" and check "Character Set", "Field Delimiter" and "Text Delimiter"</li><li>Check "Start", "Stop" and "Pause" (optional)</li><li>Click "OK"</li></ol>The Draft Message is saved as Template in your Current Account and for each Recipient a New Message is automagically saved in your Outbox ("Local Folders -&gt; Outbox"). Ready for Delivery: "File -&gt; Send Unsent Messages" </blockquote> If you need more help, feel free to ask! That's why we're here :-)