https://thunderbird.topicbox.com/groups/planning/T437cd854afcb1395
..Thunderbird loses users each day to rich ecosystems that are both clients and services, such as Gmail and Office365. These ecosystems have both hard vendor lock-ins (through interoperability issues with 3rd-pary clients) and soft lock-ins (through convenience and integration between their clients and services)
It is our goal to eventually have a similar offering so that a 100% open source, freedom-respecting alternative ecosystem is available for those who want it…