Which of the following files, when using Sendmail or a similar MTA system, will allow a user to redirect all their mail to another address and is configurable by the user themselves?

`/etc/alias` is a system-wide aliases file managed by the system administrator, not by individual users.

`/etc/mail/forwarders` is not a standard file for user-configurable mail forwarding; system-wide forwarding configurations are typically handled differently.

`~/.alias` is not a standard file for mail forwarding; it is commonly used for shell command aliases, not email redirection.

The `~/.forward` file (located in a user's home directory) is a standard mechanism in many Unix-like mail transfer agents, including Sendmail, for individual users to specify an alternative email address or program to which their incoming mail should be delivered. This file is directly controlled by the user, fitting the question's criteria.