A mailbox is a file that is the final destination for email messages. The name of the mailbox can be the user name or the identity of a specific function, such as the postmaster. Mailboxes are in the /var/mail/username file, which can exist either on the user's local system or on a remote mail server. In either instance, the mailbox is on the system to which the mail is delivered.
Mail should always be delivered to a local file system so that the user agent can pull mail from the mail spool and store it readily in the local mailbox. Do not use NFS-mounted file systems as the destination for a user's mailbox. Specifically, do not direct mail to a mail client that is mounting the /var/mail file system from a remote server. Mail for the user, in this instance, should be addressed to the mail server and not to the client host name. NFS-mounted file systems can cause problems with mail delivery and handling.
The /etc/mail/aliases file and name services such as NIS and NIS+ provide mechanisms for creating aliases for electronic mail addresses so that users do not need to know the precise local name of a user's mailbox.
The following table shows some common naming conventions for special-purpose mailboxes.
Table 26–8 Conventions for the Format of Mailbox Names
Starting with sendmail version 8, the envelope sender for mail that is sent to a group alias has been changed to the address that is expanded from the owner alias, if an owner alias exists. This change enables any mail errors to be sent to the alias owner, rather than being returned to the sender. With this change, users notice that mail that was sent to an alias looks as if it came from the alias owner, when delivered. The following alias format helps with some of the problems that are associated with this change.
mygroup: :include:/pathname/mygroup.list owner-mygroup: mygroup-request mygroup-request: sandys, ignatz |
In this example, the mygroup alias is the actual mail alias for the group. The owner-mygroup alias receives error messages. The mygroup-request alias should be used for administrative requests. This structure means that in mail sent to the mygroup alias, the envelope sender changes to mygroup-request.