Clarification about postfix configuration

[Svetlana-T]

This line causes issues with my rainloop saying 'Can't send message'. I commented it out in my postfix configuration file, and then rainloop started being able to send messages fine. What is this line useful for?

https://github.com/LukeSmithxyz/emailwiz/blob/master/emailwiz.sh#L167

[LukeSmithxyz]

Most of the reject settings in the line are to reject improperly configured email servers that send spam to yours (like pretending to be from a server they are not). Could be that your hostname or something else isn't properly configured. You can toy with which one is causing the issue by removing it, but there's a good chance there is a problem in your configuration.