Expected response code 354 but got code "554"

Expected response code 354 but got code "554", with message "554 5.5.1 Error: no valid recipients ". I am getting this error.

MAIL_DRIVER=smtp
MAIL_HOST=mail.example.net
MAIL_PORT=587
MAIL_USERNAME="noreply@example.com"
MAIL_PASSWORD="password"
MAIL_ENCRYPTION=tls

How to solve this issue.

via Chebli Mohamed