You have configured email notifications in WorldServer, and notifications and password resets are received for addresses on your domain, but are not received by users of different domain names.

In your ws-legacy.log file you see something similar to this:
 

com.sun.mail.smtp.SMTPAddressFailedException: 550 5.7.54 SMTP; Unable to relay recipient in non-accepted domain

Either set up a user on your SMTP server, and enable authentication in the WorldServer notification configuration, or configure your SMTP server to send mail to other domains without authentication.

Your SMTP server is configured not to send mail to other domains without authentication.