First up great idea - connecting the people again in the smartphone addiction age. 
How do discover / get in contact with your neighbors over an app?
I believe this is the most difficult step.
Is it like a tinder radar or something location based?
Maybe you can use a bot for this purpose (getting contact to neighbors, offer help and lending tools/stuff). @adbenitez’s simple bot already as a “friends feature” that is basically an addressbook of people where they tell a sentence about what they do and who they are.
simplebot_plugins/plugins/simplebot_friends at master · simplebot-org/simplebot_plugins · GitHub
There are ideas for chat resources to share resources like
- state for group shared webapps (like a pad, todo list or even data for games)
- a group shared calendar
But those chat resources probably won’t be implemented in the near future.
Also most email providers limit the number of recipients for a message so groups can only be as large as the person with the smallest limit on recipients, that means if someones provider only allows sending to 20 people the max group size for that person is 20.
So I’m not sure if email/deltachat is right for your project.
Maybe a small lightweight community selfhosted server or bot would be better, possible with deltachat integration for login and notifications?
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