Mozilla Thunderbird
Make the font smaller
To make the font smaller in Mozilla Thunderbird, press Ctrl + Less than. It is listed for Windows, and no Mac version is documented here.
Where it works: Writing a message
Ctrl with the comma also makes the font smaller. On a US English keyboard this character needs Shift and the comma key. The shortcut itself is unchanged.
Where this comes from
Keyboard shortcuts - Thunderbird Help
Documentation checked on 2026-09-14. That is a documentation review, not a test run inside the application.