Clicking a link in email is supposed to open the browser, but after a fresh install of Ubuntu Mint/MATE Thunderbird with Chromium-Browser does not open links at all. You are forced to copy the link, change to the browser, then paste the link to open it.
This actually worked:
In Thunderbird 11.0.1, it is simple, yet not intuitive:
- Go to Preferences (Menu Edit → Preferences).
- Click on the Attachments tab.
- In the Content Type and Action section set HTTPS, HTTP, and FTP to Use google-chrome (or other desired browser).
The other suggestions on the page did not work.