A service reports that your browser is not supported
Description: When loading a service in a tab, an error page warns that your browser is not supported.
Solution: Go to Thunderbird Preferences, view the Advanced preferences, and click General. At the bottom of the Advanced > General tab, click “Config Editor” and agree to the disclaimer about voiding your warranty. Search for the configuration setting named “general.useragent.compatMode.firefox” and changed it from it’s default value of “false” to “true” by double clicking the setting’s line. By changing this setting to true, Thunderbird reports its user agent as Firefox to any websites you visit allowing you to view most pages Firefox can.
OneNote Notebooks open in an external browser
Description: When a Notebook is clicked from within a OneNote tab in Thunderbird, the Notebook is opened in an external browser.
Workaround: Right click the Notebook and select “Open in new tab”.