Does it make sense to have a setting for receivers to require stamps too? 

Use case: if someone outside of my contacts sends me a note then they have to pay me to read it. 

 It’s possible. You just need to ask him to transfer ecash.

In Keychat, transferring ecash is just a message.Very easy. 

 It would be great if it couldn’t even get to the inbox unless there’s a stamp. 

Thanks for building this app!