Cause of default aliases to MTA-postfix

In the setup of two mail exchangers and a mail server using postfix ( MTA - mail transfer agent ). As per DNS mx record mails flow from mail exchangers to mail server vice versa.

okay. see what this /etc/aliases file does with postfix.

vi /etc/aliases
####sample of aliases ############
# Basic system aliases -- these MUST be present.
mailer-daemon: postmaster
postmaster: root
# General redirections for pseudo accounts.
bin: root
daemon: root
adm: root
lp: root
########### end ################

above file gives daemon and related aliases details. take a example, system daemons generates a log mail to aliases uid. interesting by default system daemons mails go to local machine . but postfix appends domain to name and mail exchangers keep a transport record that used to rely mail to subdomains. in above scenario system local mails are route between mail exchanger and mail server and this is pile up mail queue and slow down delivery. following changes will make local mail to delivery to local only.


modified aliases file to avoid piling of mail queue.
vi /etc/aliases
#########sample of aliases ########
# Basic system aliases -- these MUST be present.
mailer-daemon: postmaster@localhost
postmaster: root@localhost
# General redirections for pseudo accounts.
bin: root@localhost
daemon: root@localhost
adm: root@localhost
lp: root@localhost
############## end ###############