my Mailer-daemon could received mail

[chenjung]

Hi all,

Recently, I received only one mail thru mailer-daemon account that I don't know why this mail can reach and sent to mailer-daemon so I received as root.
(I'd set aliases mailer-daemon -> postmaster-> root)
Then I tried to send mail from my gmail to mailer-daemon directry but that was received a returned mail as Address Rejected that is normally.
Which is the reason for this event?

Cheers! Thank you

Chen
(CentOS, Postfix, TLS, Dovecot, Apache)

[falko]

Are there any errors in your mail log (in the /var/log/ directory)?