We’re happy to report that Thunderbird usage continues to expand.

Mozilla measures program usage by Active Daily Installations (ADI), which is the number of pings that Mozilla servers receive as installations do their daily plugin block-list update. This is not the same as the number of active users, since some users don’t access their program each day, and some installations are behind firewalls. An estimate of active monthly users is typically done by multiplying the ADI by a factor of 3.

To plot changes in Thunderbird usage over time, I’ve picked the peak ADI for each month for the last few years. Here’s the result:

Germany has long been our #1 country for usage, but in 4th quarter 2014, Japan exceeded US as the #2 country. Here’s the top 10 countries, taken from the ADI count of February 24, 2015:

Rank Country ADI 2015-02-24 1 Germany 1,711,834 2 Japan 1,002,877 3 United States 927,477 4 France 777,478 5 Italy 514,771 6 Russian Federation 494,645 7 Poland 480,496 8 Spain 282,008 9 Brazil 265,820 10 United Kingdom 254,381 All Others 2,543,493 Total 9,255,280

Country Rankings for Thunderbird Usage, February 24, 2015

The Thunderbird team is now working hard preparing our next major release, which will be Thunderbird 38 in May 2015. We’ll be blogging more about that release in the next few weeks, including reporting on the many new features that we have added.