I think that this sentence needs to be gotten rid of completely. - Webmail is fundamentally not something that can run on your own computer. The word is "web" mail, not desktop mail, it's just going to confuse users.

In addition to it being confusing, because of dynamic IPs and residential port blocking you may be able to run it on your computer, you just won't be able to do anything with it due to other internet infrastructure... - Sending mail from home is almost guaranteed to fail sometimes/often, due to dynamic ip ranges which are frequently blocked. - Port 25 and port 80 are blocked by most major american ISPs these days for residential services. Making this unusable from a home server. Not to mention it's against many ISPs terms of service to run a server from home without paying for a business package. (That's right, it's not just google fibre) - SPF records and other forms of email authentication? You would also need a third party DDNS service if using a dynamic IP.

So with all of that said, I like the interface pictures. It could be a good competitor to webmail clients like roundcube and friends.