Start the <b>beta</b> version of Thunderbird (with release version not running) and it will use the <b>default-beta</b> profile. On first use Thunderbird will create the <b>default-beta</b> profile, and it will prompt you to define your accounts. If you need to bring some data from your release profile into the beta profile, consult the <a href="https://support.mozilla.org/kb/thunderbird-beta">beta support article.</a>
Start the <b>beta</b> version of Thunderbird (with release version not running) and it will use the <b>default-beta</b> profile. On first use Thunderbird will create the <b>default-beta</b> profile, and it will prompt you to define your accounts. If you need to bring some data from your release profile into the beta profile, consult the <a href="https://support.mozilla.org/kb/thunderbird-beta">beta support article.</a>