Relay access denied

[shannaburns]

I saw some articles saying that Zimbra has default smtpd_relay_restrictions which prevent unauthorized access unless you are inside a trusted network. I also reported the following two errors when testing. What are the solutions to these two situations?
1.Relay access denied
[*] Response after data:
Error: no valid recipients
2. recipient address must contain a domain

[Chocapikk]

Um I have no idea I did a local lab, not at all intended for "Real-world" exploitation so I can't tell you honestly.