Some people in #Iran successfully use delta with national email providers when outside Internet is cut.

#deltachat designs are #OfflineFirst using delay tolerant protocols. Messages are queued when a path is blocked. email servers are made for this and run at planetary scale.
Messages crossing the border may arrive three days later but they arrive.

Peoples can stay in private touch across time and space, to the extent possible in current breakdown times. Which is what delta is about.