I realized that my server has sent too many spam but actually its not from email account that register in my SmarterMail server. I found that its coming from IP 127.0.0.1, so I deactivated the Binding Port SMTP from that (uncheck port 25(SMTP) and 587 (Submission Port)) and the spam not sending again. Maybe this one make our IP get blacklisted and take 554 by sender from our server.
Thank you Derek for your explanation.
Kind Regards,
Bayu Permadi