Using Mail Aliases:

Mail aliases are defined in the aliases file. The location of the aliases file is set in the sendmail configuration file. (You'll see this configuration file later in the chapter.) On Linux systems, the file is usually located in the /etc directory (/etc/aliases), and it is occasionally located in the /etc/mail directory. The basic format of entries in the file is:

alias: recipient

The alias is the username in the e-mail address, and recipient is the name to which the mail should be delivered. The recipient field can contain a username, another alias, or a final delivery address. Additionally, there can be multiple recipients for a single alias.

sendmail aliases perform important functions that are an essential part of creating a mail server. Mail aliases do the following:

• Specify nicknames for individual users Nicknames can be used to direct mail addressed to special names, such as postmaster or root, to the real users that do those jobs. When used in conjunction with the domain MX records covered in Linux DNS Server tutorial aliases can be used to create a standard e-mail address structure for a domain.
• Forward mail to other hosts sendmail aliases automatically forward mail to the host address included as part of the recipient address.
• Define mailing lists An alias with multiple recipients is a mailing list.