Is ethmail a login plugin + an opensource webmail?

Hi there, when i use the web.ethmail.cc, I noticed that it is very much alike the Roundcube mail. So, I guess that ethmail is redesigned with a web3 login function, and uses the traditional webmail design.Is it right?

Yes, exactly. ETHMail is a composition of couple of already existing software packages (Roundcube, Postfix, etc.) using web3 as a login/identity layer.