Composing and Formatting Messages

This chapter shows you how to compose and send email with Thunderbird. It also explains how to reply to or forward emails you have received from others. On top of that, you'll learn to add tables and to format email by changing fonts and colors. Finally, if you want to add images or attachments to an email, this will demonstrate how it's done.

Composing and sending an email message

In Thunderbird, you can write, review, and send emails to your recipients. Here's how:

  1. Click the Write button to begin work on your email.write-send-1_1.JPG

  2. Thunderbird opens a new email composition screen. You will need to do three things to create your new email:
    • Enter the email recipient's address in the To field.
    • Give the email a subject in the Subject field.
    • Type your message in the Message Body pane.
  3. After you are finished writing, you should review your email before sending it. Notice that Thunderbird has underlined the misspelled words "Pizze" and "resteurant" with red, squiggly lines. To fix these spelling errors and to look for any other misspelled words, click the Spell button.
  4. The spell checker suggests that you replace "resteurant" with "restaurant". Click the Replace button to make the correction or click the Ignore button to leave it unchanged. To close the Check Spelling dialog box, click the Close button.
  5. When you are satisfied with your message, send it by clicking the Send button.
  6. Thunderbird sends your message to the recipients and it saves a copy of it to your email account’s Sent folder.

Some notes about writing and sending emails

  • In Thunderbird, you cannot recall an email after you've sent it. When it's gone, it's gone.
  • See the instructions in the Format section to see how you can change the look and feel of your email.

Replying to or forwarding an email

You'll often receive emails that require a reply and other ones that you'll want to forward to a third party. Here's how to use Thunderbird to handle these tasks.


  1. Go to your Inbox and select an email from the message list by clicking it. Then click the Reply button to open a composition window for the email reply.t_bird_reply_1.jpg
  2. Since you are replying to an email, there is no need to enter the recipient's address because Thunderbird has already put it in the To: field. Also, Thunderbird will put Re: at the start of your subject to show the recipient that this is a reply e- mail.
  3. You need to do three things to complete your reply.
    • Type your reply in the message pane.
    • Review and check the spelling.
    • Click the Send button to send it.
  4. Thunderbird sends your message to the recipient and it saves a copy of it to your email account’s Sent folder.


  1. Go to your Inbox and select an email from the message list by clicking it. Then click the Forward button to open a composition window for the email.t_bird_forward_1_v2.jpg
  2. You need to do four things to complete your message. Note that Thunderbird puts Fwd: at the start of your subject to show the recipient that this is a forwarded email.
    • Enter the email address of the recipient in the To: field.
    • Type your reply in the message pane.
    • Review and check the spelling.
    • Click the Send button to send it.
  3. Thunderbird sends your message to the recipient and it saves a copy of it to your email account’s Sent folder.

A few other notes about replying to and forwarding emails.

  • You can reply to all the recipients of an email by using the Reply All button instead of the Reply button.
  • You can add or remove recipients from the email to the email that you are replying to or forwarding.
  • If you need to, you can change the email's subject.

Adding recipients to messages

There are several ways to add email addresses to your messages. Of course, you can simply type them directly into the email or you can copy and paste them from other emails. However, if you have a lot of contacts, you can use the Thunderbird Address Book to supply email addresses for your messages via Thunderbird's address auto-completion feature and the Contacts Sidebar. Let's take a look at how to use them.

Email address auto-completion

  1. After you start typing a contact name or an email address that is in your Address Book, Thunderbird auto-completes it for you. In this example, if you type the letters "jan", Thunderbird finds Jane Doe in the Address Book. To add the this contact to your message, you hit the Enter key or click the contact with your mouse.
  2. If Thunderbird finds multiple contacts it will give you a list from which to choose one. When you type the letter "j", Thunderbird finds John Smith and Jane Doe in the Address Book. Click the desired contact to add it to the email.

Contacts sidebar

The message composition window has a Contacts sidebar that lists your contacts from the Thunderbird Address Book.

  1. You open it by using the F9 key or by going to the View menu and then clicking Contacts Sidebar.
    Pick an address book by clicking the list under the Address Book label and then select the one you want to use. Once you do this, the contacts from that book are listed in the sidebar.
  2. Double click a contact to add it to your message as a recipient. Another way to add a contact is to select one from the list (with a single click) and then click the Add to To, the Add to Cc, or the Add to Bcc buttons. 

What's the difference between To, Cc, and Bcc?

  • To - This is usually the main recipient of the email. Frequently, this is the person (or persons) that you expect to act on your email.
  • Cc - The abbreviation "cc" means "carbon copy" (a term that is a leftover from the old typewriter days). If you "cc" people on an email, your intent is to tell them that something is happening but that no action is expected of them. Every recipient of an email can see who was "cc'ed" on the email.
  • Bcc - This means "blind cc". To "bcc" a person on an email is to send that person an email but not let any other recipient know that he or she got it. This can be useful when you want to send an email to a large group of people and you either don't want everyone to know who got it or you simply don't want to expose your friend's email addresses to everyone in the group. 

Changing a To recipient to a Cc or Bcc recipient

  1. Click the To: label next to the recipient that you want to change to Cc or Bcc.
  2. Click either Cc or Bcc.

Formatting Messages

HTML and plain text formats

You can format the text in your email as HTML or as plain text. If you use HTML, you work in much the same way as when using a word processor such as Open Office Write or AbiWord. You get a lot of control over the appearance of your message. You can change fonts, set font styles and colors, insert tables, and add pictures. Plain text is exactly what it sounds like: text only with no formatting at all.

HTML/Rich Text Email Plain Text Email
formatted_email_html_1.jpg formatted_email_html_2.jpg

The default outgoing message format in Thunderbird is HTML. It can be changed by going to the Option menu, pointing to Format, and picking from one of the four displayed options.

  • Auto-Detect - Thunderbird looks up an email address in your address book. It uses the email format that it finds there. If it doesn't find a format it will send the message as Plain and Rich (HTML) text.
  • Plain Text Only - Plain text with no formatting
  • Rich Text (HTML) - Rich Text (HTML)
  • Plain and Rich (HTML) Text - The message is sent as both plain text and HTML.

Format bar

The format bar is visible when you use the HTML format. To use it, you highlight the text that you want formatted and then select the appropriate format button from the bar.composition_toolbar.jpg

 ID  Item Options
 1 Text Style Body Text, Paragraph,Header sizes 1-6, Address, and Unformatted.
 2 Font Type Variable width, fixed width, fonts installed on your computer.
 3 Font Color Text color picker.
 4 Font Size Click the larger icon to enlarge the font. Click the smaller icon to make it smaller.
 5 Font Style Bold, italic, or underline.
 6 Lists Numbered list or bullet list.
 7 Indent Click the right icon to indent text to the right. Click the left to un-indent it.
 8 Alignment Left, right, center, or justify text.
 9 Insert Add links, anchors, images, horizontal lines, or tables.
 10 Emoticons Add one to show how you're feeling!

Here's an example of how you use the format bar.

  1. You've just invited a friend to go cycling with you.
    Let's go cycling today. The weather be will perfect for a ride in the mountains. Better bring low gears for the big climbs!
  2. You want to change the font color to blue so you highlight  the text, click the Font Color button, pick blue , and click OK.
  3. To make the word perfect bold, you highlight "perfect" and click the Bold button.
  4. To make the word low smaller, click the small font size button. To make the word "big" larger, click the large font size button.
  5. Your message:

 Note that Thunderbird does not display the format bar when you use the plain text format. 

Images and attachments

Inserting pictures into a message

Here's how to put a picture into the body of your Rich Text(HTML) email.

  1. Click the format toolbar's insert icon and select Image from the list.

  2. The Image Properties dialog box opens. Click the Choose File button to find a picture on your computer.write-insert-photo-1_v2_1.jpg

  3. The Select Image File dialog box opens. Pick a picture from your computer and click the Open button.  picture_chooser_v2.jpg
  4. Thunderbird asks you to add alternative text to your picture. This text ensures that the reader sees some information about the picture even if the email software doesn't display it. If you don't want to enter this text then select the Don't use alternative text radio button. Click the OK button to continue.
  5. If you have selected not to use alternative text, Thunderbird may ask you to confirm your decision. Click OK to continue.
  6. The picture is inserted into your email.
  7. To delete a picture from an email, click the picture and then press the Delete key on your keyboard.

Adding attachments

One of email's convenient features is its ability to carry a document to the recipient. This works the same for both Plain Text and HTML emails. Be careful of the size of your attachments because most email providers limit attachment size. The maximum size is frequently about 10 MB but you should check with your provider to be sure.

Here's how to attach a file to an email.

  1. In the Thunderbird message composition window click, the Attach button.
  2. On your computer, find a file that you want to attach. This could be just about any type of file: a picture, a PDF file, a spreadsheet, or a video. Note that some providers may not send certain types of files - like application or script files - because of security concerns. A malevolent sender could send a script that would run when opened and then do damage to someone's computer.
  3. Click Open to continue.
  4. The file is now attached to the email. You should see a list of attachments in the Attachments pane in the upper right corner.
  5. To remove a picture from an email, go to the Attachments pane, click the picture, and then press the Delete key on your keyboard.

Adding and formatting tables

You have many options for adding and formatting tables when composing a new message. You can use a default table, which looks like this:

However, you may want to play around with formatting to make your table look more presentable.

Inserting tables into a message

  1. Go to the Insert menu and click Table
  2. The Table properties dialogue box opens. Click the OK button right away, or until after you have applied formatting.

Applying formatting to tables

  1. In the Table properties dialog box, click Advanced Edit.
  2. The Table attributes dialogue box opens. Select an attribute from the HTML Attributes menu.



Signatures are blocks of text that are automatically appended to every message that you send (including both new messages and replies to incoming messages). They are generally used to provide additional contact information, legal terms or some other boilerplate information that is relevant to every email. For example, an email signature might say something like:

John Doe
The Big Example Organization

Signatures are created in Thunderbird's Account Settings interface. Go to the Tools menu (or the Edit menu on Ubuntu) and select Account Settings. Then, in the left panel of the Account Settings window, select the account for which you want to create a signature.


If you have multiple email accounts, you must configure signatures separately for each account.

Plain-text signatures

To configure a plain-text signature, enter the text you want to append to each outgoing message in the Signature text field. Plain text signatures work with messages formatted both in HTML and in text.

Creating a signature like this...


...results in... 


 HTML signatures

To use HTML formatting in your signature, check Use HTML and format the signature text with the HTML markup that you want to use. Note that if you send messages in text (rather than HTML) format, text characters will be substituted for the HTML markup.

Creating a signature like this... 



 ...results in...


Signatures stored in files

Alternatively, you can upload a file that contains your signature. Check Attach the signature from a file instead and the click Choose to select the file. The file can contain either plain or HTML-formatted text. If you have an HTML-formatted signature, the message recipient must be able to view HTML-formatted messages in their email program. If they have disabled this ability, the signature will be rendered in as text and images will not be displayed.

One way to create a signature file is by using the Thunderbird composer. As an example, create a new HTML-formatted message in Thunderbird (go to the File menu, point to New and click Message). Make sure that the HTML toolbar is displayed. (If it is not displayed, you are composing a message formatted in text, not HTML. To change to HTML, go to the Options menu, point to Format and click Rich Text (HTML) Only.)

  1. Compose and format your signature as desired. Note that numerous formatting functions are available from the Insert and Format menus.  _1
  2. Go to the File menu, point to Save As, and click File. Make sure "HTML files" is selected, and then specify a file name and click Save.
  3. Close the message window and discard the message without saving.
  4. Open the Account Settings (go to the Tools menu and click Account Settings) and select the email account in the panel on the left.
  5. Check Attach the signature from a file, click Choose and navigate to the file you created.

Including image files in signatures

To include an image file from your local computer in a signature, follow the steps above to create an HTML signature. When you are composing the signature contents, though, go to the Insert menu and click Image to specify the desired image. 


In addition to selecting the image file, use this dialog to configure other aspects of the image, such as the size, a URL link, its position with regards to the text, etc.

You can also specify an image located on a web server as part of your attachment. Just specify the image URL in the field where you would otherwise specify the file name. If you check Attach this image to the message, the image will be included as an attachment. If you do not attach the image, the people receiving your message Internet connection to view the image. Also, keep in mind that for security reasons many people configure their email programs to block remote content, which would prevent the image from displaying unless it was attached to the message.

Signature Delimiter

When placing a signature in a text based email, a default "-- " (dash, dash, space) is inserted to separate text. To switch it off for all identities of your accounts, you can access your Configuration Console and change mail.identity.default.suppress_signature_separator to "true".

To access the *Configuration Console: 

  • For Windows, select Tools > Options. Select General, and click Configuration
  • For Linux, select Edit, and then Options.
  • For Mac OSX, select ThunderbirdPreferences. In the Advanced tab, click Config Editor.

It's important to note that removing the signature makes it a part of the message you compose. When replying to messages where the signature is placed below your reply, but above the quote, signatures won't be removed if you choose to change identities.  

The preference also provides a way to always add the signature separator. Using the Configuration Console as mentioned above, you can set the preference to "true" and manually add "-- " (dash, dash, space) separators to your signature. While this makes it consistent, quotes become part of your signature and are removed when you reply to them.


*In modifying any preferences in your configuration console, you may run the risk of harming the stability, security and performance of your Thunderbird application.