https://help.runbox.com/email-program-settings/ 
https://www.getmailbird.com/setup/access-runbox-com-via-imap-smtp 
https://www.mailjerry.com/runbox-imap-settings/

https://gist.github.com/bachors/8d8a1aa482bb3eabdff1 
https://github.com/developarts/imap-client/blob/master/example.php