vCard is a file format standard for electronic business cards. vCards can contain name and address information, phone numbers, e-mail addresses, URLs, logos, photographs, etc. vCards are often attached to messages because:

• They enable your recipient to quickly and reliably add your contact information to their personal address book.
• They help you to minimize your signature because your contact information is available in the vCard (and therefore doesn't need to be included at the bottom of every email message).

See vCard on Wikipedia for more details about this format.

How to attach your vCard to a message

To automatically attach your vCard to all outgoing messages:

1. Go to the Tools > Account Settings menu. Go to the Edit > Account Settings menu.
2. Click the Edit card… button to configure your virtual card information.
3. Check Attach my vCard to message as shown below if you want to attach your vCard to all your outgoing messages by default.

Rather than automatically attaching your vCard, you can attach it to individual messages. While composing the message, click the arrow near the Attach button and check or uncheck the Personal Card (vCard) menu item.

How to deal with received vCards

When a vCard is attached to a message, the message will have an attachment with a *.vcf extension. Thunderbird will automatically recognize and preview this attachment in the message body, as shown below:

Click the icon to open the vCard and add it to your address book.