Here at Excontinuum we have a full-scale Mail system. If you want to check your mails on the go and don’t have a configured smartphone with you, we offer two different services.
The first option is shortly explained here.
We’re using Roundcube, a light weighted,

Basically Rocket.Chat is built like an IRC client; you can connect to various public channels or create private conversations for groups or individuals.
Moreover Rocket.Chat can be personalized by many different add-ons and modules, e.g. a Bot. By using WebRTC video conferencing, VoIP calls,