28.10. 郵件使用者代理程式
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## 28.10. 郵件使用者代理程式

Contributed by Marc Silver.

A MUA is an application that is used to send and receive email. As email “evolves” and becomes more complex, MUAs are becoming increasingly powerful and provide users increased functionality and flexibility. The `mail` category of the FreeBSD Ports Collection contains numerous MUAs. These include graphical email clients such as Evolution or Balsa and console based clients such as mutt or alpine.

### 28.10.1. `mail`

mail(1) is the default MUA installed with FreeBSD. It is a console based MUA that offers the basic functionality required to send and receive text-based email. It provides limited attachment support and can only access local mailboxes.

Although `mail` does not natively support interaction with POP or IMAP servers, these mailboxes may be downloaded to a local `mbox` using an application such as fetchmail.

In order to send and receive email, run `mail`:

    % mail

The contents of the user's mailbox in `/var/mail` are automatically read by `mail`. Should the mailbox be empty, the utility exits with a message indicating that no mail could be found. If mail exists, the application interface starts, and a list of messages will be displayed. Messages are automatically numbered, as can be seen in the following example:

    Mail version 8.1 6/6/93.  Type ? for help.
    "/var/mail/marcs": 3 messages 3 new
    >N  1 root@localhost        Mon Mar  8 14:05  14/510   "test"
     N  2 root@localhost        Mon Mar  8 14:05  14/509   "user account"
     N  3 root@localhost        Mon Mar  8 14:05  14/509   "sample"

Messages can now be read by typing t followed by the message number. This example reads the first email:

    & t 1
    Message 1:
    From root@localhost  Mon Mar  8 14:05:52 2004
    X-Original-To: marcs@localhost
    Delivered-To: marcs@localhost
    To: marcs@localhost
    Subject: test
    Date: Mon,  8 Mar 2004 14:05:52 +0200 (SAST)
    From: root@localhost (Charlie Root)

    This is a test message, please reply if you receive it.

As seen in this example, the message will be displayed with full headers. To display the list of messages again, press h.

If the email requires a reply, press either R or r `mail` keys. R instructs `mail` to reply only to the sender of the email, while r replies to all other recipients of the message. These commands can be suffixed with the mail number of the message to reply to. After typing the response, the end of the message should be marked by a single . on its own line. An example can be seen below:

    & R 1
    To: root@localhost
    Subject: Re: test

    Thank you, I did get your email.
    .
    EOT

In order to send a new email, press m, followed by the recipient email address. Multiple recipients may be specified by separating each address with the , delimiter. The subject of the message may then be entered, followed by the message contents. The end of the message should be specified by putting a single . on its own line.

    & mail root@localhost
    Subject: I mastered mail

    Now I can send and receive email using mail ... :)
    .
    EOT

While using `mail`, press ? to display help at any time. Refer to mail(1) for more help on how to use `mail`.

### 注意:

mail(1) was not designed to handle attachments and thus deals with them poorly. Newer MUAs handle attachments in a more intelligent way. Users who prefer to use `mail` may find the converters/mpack port to be of considerable use.

### 28.10.2. mutt

mutt is a powerful MUA, with many features, including:

- The ability to thread messages.

- PGP support for digital signing and encryption of email.

- MIME support.

- Maildir support.

- Highly customizable.

Refer to `http://www.mutt.org` for more information on mutt.

mutt may be installed using the mail/mutt port. After the port has been installed, mutt can be started by issuing the following command:

    % mutt

mutt will automatically read and display the contents of the user mailbox in `/var/mail`. If no mails are found, mutt will wait for commands from the user. The example below shows mutt displaying a list of messages:

To read an email, select it using the cursor keys and press Enter. An example of mutt displaying email can be seen below:

Similar to mail(1), mutt can be used to reply only to the sender of the message as well as to all recipients. To reply only to the sender of the email, press r. To send a group reply to the original sender as well as all the message recipients, press g.

### 注意:

By default, mutt uses the vi(1) editor for creating and replying to emails. Each user can customize this by creating or editing the `.muttrc` in their home directory and setting the `editor` variable or by setting the `EDITOR` environment variable. Refer to `http://www.mutt.org/` for more information about configuring mutt.

To compose a new mail message, press m. After a valid subject has been given, mutt will start vi(1) so the email can be written. Once the contents of the email are complete, save and quit from `vi`. mutt will resume, displaying a summary screen of the mail that is to be delivered. In order to send the mail, press y. An example of the summary screen can be seen below:

mutt contains extensive help which can be accessed from most of the menus by pressing ?. The top line also displays the keyboard shortcuts where appropriate.

### 28.10.3. alpine

alpine is aimed at a beginner user, but also includes some advanced features.

### 警告:

alpine has had several remote vulnerabilities discovered in the past, which allowed remote attackers to execute arbitrary code as users on the local system, by the action of sending a specially-prepared email. While known problems have been fixed, alpine code is written in an insecure style and the FreeBSD Security Officer believes there are likely to be other undiscovered vulnerabilities. Users install alpine at their own risk.

The current version of alpine may be installed using the mail/alpine port. Once the port has installed, alpine can be started by issuing the following command:

    % alpine

The first time alpine runs, it displays a greeting page with a brief introduction, as well as a request from the alpine development team to send an anonymous email message allowing them to judge how many users are using their client. To send this anonymous message, press Enter. Alternatively, press E to exit the greeting without sending an anonymous message. An example of the greeting page is shown below:

The main menu is then presented, which can be navigated using the cursor keys. This main menu provides shortcuts for the composing new mails, browsing mail directories, and administering address book entries. Below the main menu, relevant keyboard shortcuts to perform functions specific to the task at hand are shown.

The default directory opened by alpine is `inbox`. To view the message index, press I, or select the MESSAGE INDEX option shown below:

The message index shows messages in the current directory and can be navigated by using the cursor keys. Highlighted messages can be read by pressing Enter.

In the screenshot below, a sample message is displayed by alpine. Contextual keyboard shortcuts are displayed at the bottom of the screen. An example of one of a shortcut is r, which tells the MUA to reply to the current message being displayed.

Replying to an email in alpine is done using the pico editor, which is installed by default with alpine. pico makes it easy to navigate the message and is easier for novice users to use than vi(1) or mail(1). Once the reply is complete, the message can be sent by pressing Ctrl+X. alpine will ask for confirmation before sending the message.

alpine can be customized using the SETUP option from the main menu. Consult `http://www.washington.edu/alpine/` for more information.

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