1) Boot and join a new node to your cell.
* exo -d ./gmail_node node init
* exo -d ./gmail_node cell join (and exo cell node add on the main node, with no roles)
2) Copy gmail daemon config to your node directory.
* cp ../../examples/gmail.conf ./gmail_node/
3) Visit Google API Console to obtain a OAuth 2.0 Client ID and
download client_secret.json credentials file. Move file in the node folder (ex: ./gmail_node)
4) Login to your Gmail account (at repo root) and follow console instructions to authenticate with Gmail.
* exm -d ./gmail_node gmail login <youremail@gmail.com>
5) Start the daemon.
* exm -d ./gmail_node gmail daemon