This is an email service which costs 12€/year (around $13). They donate half of their income to associations fighting for the environment. Their accounting is public for greater transparency.
For this price, you have an email account (with a large choice of domain) and a cloud (2Go). Lot of features like your emails environment impact, an alert when you have too emails, one forum for the community, free donations, and more. Tools are open-source (Roundcube, Owncloud, phpBB). This is good for environment and respects your privacy.
Obviously, for the impact on the environment, this service is more adapted to French people, since the servers are in France.
To subscribe, follow this link: https://mail.ecomail.earth/invitation.html?uniqid=5e9082721b429
Yes, it’s IMAP compatible. Sorry, I forgot specs :
https://www.ecomail.earth/en/le-service-en
And, for their custom app, the development has just started.