Add SimpleLogin to webmail_hosts

[nguyenkims]

SimpleLogin is a open-source email forwarder https://github.com/simple-login/app

[getgray]

This does not seem like a tool that would need a bypass to postscreen, nor would we want it to be.

[nguyenkims]

@getgray can you elaborate, please? It's used to protect our email address and can be also used as a "light" email solution for business ( a bit like Zoho in this regard).