How does this actually work?

[lukas-remis]

Hi,

Just found this project and it looks very interesting, but the description is rather vague.
How does it actually work? If I understand correctly it's an email client, not a server?
I was trying to test it at 0.email - but it seems it works only on top of Gmail. Does it work with any other email accounts? Does it actually pull the emails from the accounts?

Thanks,
Lukas