I would like to transfer the email configuration to my new MacBook. Is that possible?
You can just move the configuration folder to the new machine:
* Mac: ~/Library/Application Support/Mailspring
* Windows: C:\Users\<Your User>\AppData\Roaming\Mailspring
* Linux: $XDG_CONFIG_HOME/Mailspring or ~/.config/Mailspring
Then you will need to reconnect your mail accounts as the encrypted passwords cannot be transferred.