Question: he server response was 5.7.0 must issue a starttls command first?
Answer: The server response was: 5.7. 0 Must issue a STARTTLS command first: This error means that the transport layer security (TLS) needs to be set to "Yes" in your SMTP settings. The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.