Fedora 21
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Virtual Domain Settings
Configure Postfix to use Virtulal Domain to send an email with another domain name different from original domain.
For example,
present domain name ⇒ srv.world
new domain name ⇒ virtual.host
a User [fedora] has an email address [fedora@mail.srv.world],
a User [redhat] has an email address [fedora@mail.virtual.host],
the user [redhat] uses the same name for before [@] with [fedora].
[1] Configure Virtual Domain Settings.
[root@mail ~]#
vi /etc/postfix/main.cf
# add follows to the end

virtual_alias_domains = virtual.host
virtual_alias_maps = hash:/etc/postfix/virtual
[root@mail ~]#
vi /etc/postfix/virtual
# add follows to the head

fedora@mail.virtual.host redhat
[root@mail ~]#
postmap /etc/postfix/virtual

[root@mail ~]#
systemctl reload postfix

[2] Set new account to Email client and make sure to be able to send emails.