It is possible to do, but a bad idea in most cases. **Most applications leak sensitive information when using with (or possibly without) Tor.** Less importantly, how necessary is it that Google doesn't know where you logged into your email. 

Tor Project has a page about [Torifying][1] and instructions on [specific applications.][2]

For Mozilla Thunderbird it is [recommended][3] to use [Torbirdy.][4] Installation instructions can be found [here.][5]

For a torrenting take a look at t[his question.][6]


  [1]: https://trac.torproject.org/projects/tor/wiki/doc/TorifyHOWTO
  [2]: https://trac.torproject.org/projects/tor/wiki/doc/TorifyHOWTO#Clientapplications
  [3]: https://trac.torproject.org/projects/tor/wiki/doc/TorifyHOWTO/EMail/Thunderbird
  [4]: https://trac.torproject.org/projects/tor/wiki/torbirdy
  [5]: https://trac.torproject.org/projects/tor/wiki/torbirdy#SetupSteps
  [6]: https://tor.stackexchange.com/questions/64/how-can-bittorrent-traffic-be-anonymized-with-tor/68#68