Aliases

An alias is an alternate name. For electronic mail, you can use aliases to assign a mailbox location or to define mailing lists.

For large sites, the mail alias typically defines the location of a mailbox. Providing a mail alias is like providing a mail stop as part of the address for an individual at a large corporation. If you do not provide the mail stop, the mail is delivered to a central address. Extra effort is required to determine where within the building the mail is to be delivered, and the possibility of error increases. For example, if two people named Kevin Smith are in the same building, only one of them will get mail.

Use domains and location-independent addresses as much as possible when you create mailing lists. To enhance portability and flexibility of alias files, make your alias entries in mailing lists as generic and system-independent as possible. For example, if you have a user named ignatz on system mars, in domain eng.acme.com, create the alias ignatz@eng instead of ignatz@mars. If user ignatz changes the name of his system but remains within the engineering domain, you do not need to update alias files to reflect the change in system name.

When creating alias entries, type one alias per line. You should have only one entry that contains the user's system name. For example, you could create the following entries for user ignatz:

ignatz: iggy.ignatz
iggyi: iggy.ignatz
iggy.ignatz: ignatz@mars

You can create an alias for local names or domains. For example, an alias entry for user fred who has a mailbox on the system mars and who is in the domain planets could have this entry in the NIS+ aliases table:

fred: fred@planets

When creating mail lists that include users outside your domain, create the alias with the user name and the domain name. For example, if you have a user named smallberries on system privet, in domain mgmt.acme.com, create the alias as smallberries@mgmt.acme.com.

The email address of the sender is now automatically translated to a fully qualified domain name when mail goes outside the user's domain.

Uses for Aliases Files

You create mail aliases for global use in the NIS+ mail_aliases table, the NIS aliases map, or in local /etc/mail/aliases files. You can also create and administer mailing lists using the same alias files.

Depending on the configuration of your mail services, you can administer aliases by using the NIS or NIS+ name service to maintain a global aliases database or by updating all the local /etc/mail/aliases files to keep them synchronized.

Users can also create and use aliases. They can create aliases either in their local ~/.mailrc file, which only they can use, or in their local /etc/mail/aliases file, which can be used by anyone. Users cannot normally create or administer NIS or NIS+ alias files.