You have added several domains/Email address in Protocols -> Domains and notice that the appliance is rejecting some emails and showing the error:
Error: "Rejected message for a nonlocal recipient"
The localpart of an e-mail address is case sensitive.
Please, upgrade to version 9.5 and be sure that the option
Protocols -> Settings -> Address Handling -> "Ignore the text case of the local part of the addresses in Address Masquerading, Aliases and Domains" is ENABLED.