Understanding Exim4's /etc/aliases

Question

Regarding this exim /etc/aliases man page

I am not sure how /etc/aliases works. The

/etc/aliases
   The file should contain lins of the form
   name: address, address, ...

I looked in /usr/share/doc/exim4-base/spec.txt.gz, but all I want is an example of the format of the aliases.

Is it

root:  bobjoe@mysite.com, Robbiejoe@mysite.com, bobjoe@mysecondsite.com

Where root is the login username on the Linux system, and the aliases that trail after it are (email addresses that go to root's inbox)

Or is it

root:  bobjoe, Robbiejoe

Where the domain name is left out.. so the alias file doesn't care about domain..??

And so how can you route bobjoe@mysecondsite.com to the root user?

Answer 1

/etc/aliases is used to redirect mail for users in the local domain (the domain the exim4 server belongs to). Therefore, if you were to have a line like

joe:   joseph@another.domain.com, josephine@some.where.else

then email addressed to joe (and joe being a local user on the mail server) would be sent to the other two email addresses instead.

If you want to redirect email addressed to bobjoe@mysecondsite.com to root, then you would first of all need to make sure that your mail server is configured to process messages for the domain mysecondsite.com (i.e. mysecondsite.com has to be a relay domain, and the MX records for it have to point to your mail server), and then (if you wanted to use /etc/aliases) bobjoe would need to have a local account, plus you need a line in /etc/aliases of the form

bobjoe:   root

.

For mail servers with hundreds of users that would be a real pain in the backside, so I would recommend using other methods of aliasing, e.g. vexim.