Make Thunderbird the Default Mail Client

If Thunderbird is specified as your system’s default email application, it will integrate with other applications (such as word processors and web browsers). For example, when you click an email address link (like ““) on a web page or invoke a mail function (such as “Send to”) from a word processor, Thunderbird will launch and open a message composition window.

Unfortunately, there is a great deal of variability among operating systems and applications regarding how the default mail client is specified. If the suggestions on this page do not solve your problem, consult the specific application or operating system’s documentation for instructions on how to set the default email client. Also, see the Default mail client article on the MozillaZine website for more tips.

Force Thunderbird to check if it is the default

Thunderbird can be configured to check if it is the operating system’s default mail client each time it is started.

  1. Select Tools > Options.
  2. On the Advanced panel, select the General tab.
  3. Make sure that “Always check to see if Thunderbird is the default mail client on startup” is checked.
  4. Click Check Now to check if Thunderbird is set as the default mail client immediately.


  • If you want to set Thunderbird as the default client for e-mail, newsgroups or feeds, check the corresponding boxes and click OK. When a box is grayed out, Thunderbird is already set as the default client for that purpose.
  • If you set Thunderbird to be the default mail client, other applications (such as your web browser or word processing application) may need to be restarted to be aware of the change.

Set Thunderbird as the operating system default

Various versions of Windows have various ways of configuring the default email application. In general, go to Start > Control Panel > Add or Remove Programs > Set Program Access or Defaults. In the Custom settings, configure Thunderbird as the default email application.

Set Thunderbird as an application default

In some cases (such as Firefox on KDE Linux), the application doesn’t check the operating system preferences to determine the default email application. When that is the case, you must set the default in the application itself. Refer to the application documentation for instructions.