1. CS 497C – Introduction to UNIX Lecture 38: - Electronic Mail Chin-Chih Chang chang@cs.twsu.edu chang@cs.twsu.edu

2. Email Basics Email is a inexpensive, informal, and fast method off-line communication. An email address may consist of only the username if the user is on the same host or may have the form username@hostname or username@domainname. Incoming mail is appended to a text file (the mailbox) named after the user-id in /var/mail (SVR4) or /var/spool/mail (Linux).

3. mail, elm, and pine The earliest mail handling program is mail, but elm and pine are more powerful and user-friendly. Viewed mail is often stored in $HOME/mbox, but elm and pine also use separate folders in $HOME/Mail. You can reply to mail, forward, delete, or save a mail message with simple keystrokes.

4. pine: Yet Another Mail Program You can search for a pattern, and also take suitable action on junk mail (spam). Using pine, you can also defer dispatch of mail, maintain an address book and spell- checking your messages. pine can be configured to automatically execute a series of keystrokes on startup. Elm can be configured by editing the file $HOME/.elm/elmrc. Pine uses $HOME/.pinerc.

5. .signature and.forward: Two Important Fiels You can redirect your mail by placing the desired email address in $HOME/.forward. romeo@yahoo.com You can ensure that every message is accompanied by your personal details by placing them in the.signature file, which all mailers use by default. Mail handling requires the work of three agencies:

6. How Mail Works –Mail user agent (MUA) – For reading and sending mail. –Mail transport agent (MTA) – For forwarding mail between machines. –Mail delivery agent (MDA) – For delivering mail to the recipients’ mailboxes. In this three-tiered arrangement, the mail user agent (MUA) like pine or elm acts as the user’s front-end.

7. How Mail Works Mail is transported using the Simple Mail Transfer Protocol (SMTP). SMTP hands over the message to the delivery agent. Mail is fetched from a remote site with the Post Office Protocol (POP) often using a dialup line. Netscape Messenger or Microsoft Outlook Express uses its own SMTP and POP client features to send mail and fetch it from POP server.

8. Netscape Messenger and Microsoft Outlook Express Mail messages can be sorted in any sequence or moved to any folder by using the mouse. Messenger can group messages that emanate from another as a thread. Messenger and Outlook can view GIF and JPEG graphics inline along with the message.

9. Netscape Messenger and Microsoft Outlook Express Eudora is another popular email program. Web-based email services are more popular in these days. The vacation command sends a predetermined message to everyone who sends a message to a user on vacation. It is invoked from a user’s.forward file. For example, your.forward file might have:

10. Vacation: Going on Leave \eric, "|/usr/bin/vacation eric” which would send messages to you (assuming your login name was eric ) and reply to any messages for “eric''.