1. How can I configure SMTP authentication an MDaemon 13.6 server client?
From the MDaemon console:
Select Security>>Select the Security Settings option>>Expand Sender Authentication>>Select SMTP option>>Select the authentication is always required when email is from the local accounts>>select Apply option>>Select OK
With SMTP Authentication enabled on the server, the local sending email to the clients will need to be configured to send messages using SMTP Authentication.
For Outlook 2013:
Select File>>Select Account Settings>>Select Account Settings from the drop down>>Select the MDaemon account>>Select Change>>Select More Settings>>Then, select the Outgoing Server tab>>SMTP requires authentication>>Select the radio button for incoming email server>>Select OK
For Outlook 2010:
Choose File>>Select Account Settings from the drop down>>Select the MDaemon account>>Select Change>>Select More Settings...>>Select the Outgoing Server tab>>SMTP requires authentication>>Select the radio button for use the same settings for incoming mail server>>Select OK
2. How can I solve the SMTP error 554 of MDaemon?
You can solve your issue. Please follow this link:- http://stackoverflow.com/questions/221416/smtp-error-554
3. How can I tell why an inbound or outbound message bounced, based on the SMTP reply code?
Now you understand about it, please follow this link:https://support.google.com/postini/answer/134416?hl=en
4. What are STMP Codes error and STMP Status code of MDaemon?
Please read this article, you will know it. Here is the link: https://www.scribd.com/doc/36160456/SMTP-Server-Status-Codes-and-SMTP-Error-Codes