If I understood well: 1/ it works offline (think git vs svn) - so you can work in a train for instance 2/ if you test your app with real data (ie: many differ

If I understood well: 1/ it works offline (think git vs svn) - so you can work in a train for instance 2/ if you test your app with real data (ie: many different emails), you're sure no email will go out by mistake 3/ you can use as many recipients as you want (with any kind of address) and see the emails right away I could be wrong though - my understanding!