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mail_intro(7) Miscellaneous Information Manual mail_intro(7) NAME mail_intro - Introductory information on the DIGITAL UNIX mail system DESCRIPTION The DIGITAL UNIX mail system enables you to exchange mail with other users on your system, as well as with other systems connected to your local network and with users on other networks (provided your system and network are connected to other networks). Mail System Concepts Mail systems consist of the following components: User agent - The user agent provides the interface through which you interact with the mail system. Generally, the user interface enables you to create, send, re- ceive, read, save, and manage your mail messages. DIGITAL UNIX provides the following user agents: Mail or mailx The Rand Message Handling program (MH) DECwindows Mail For more information on how to use these interfaces, see the DECwindows User's Guide and the Command and Shell User's Guide. Transport agent - The transport agent provides an interface be- tween the user agents and the delivery agents. Delivery agent - The delivery agent provides the mechanism for delivering the mail messages between users, systems, and networks. In DIGITAL UNIX, the sendmail program acts as both the transport and delivery agent. It does so by implementing the Simple Mail Transfer Protocol (SMTP), which is the specification for the Internet's delivery agent. Initially standards did not exist for mail addresses and computer net- works. Many different address formats and network protocols exist. Mail programs must interact with different network protocols, as well as recognize and reformat different mail address formats. Fortunately, these difficulties were recognized and standards, such as the Standard for the Format of ARPA Internet Text Messages (RFC 822) and The Domain Naming Convention for Internet User Applications (RFC 819), emerged. A mail program still must recognize addresses in various formats and com- municate with different network protocols. The sendmail program ad- dresses these issues through the use of the sendmail.cf configuration file. The Sendmail Configuration File The sendmail.cf configuration file provides the sendmail program with the information to perform the following tasks: Choose delivery agents Use address rewriting rules Define mail header information Perform some routing When it starts, the sendmail program reads the sendmail.cf configura- tion file. The information in the sendmail.cf configuration file en- ables sendmail to rewrite the addresses of mail it receives into the address form expected by the mail delivery agent. It also enables send- mail to set parameters and arguments to the mail delivery program. The configuration file contains information that is used for the fol- lowing functions: Define message precedence for mail delivery Define administrative IDs to override the sender's address Define message headings Define the mail daemon to use Set options used by the sendmail command The default DIGITAL UNIX configuration file (located in /var/adm/send- mail/sendmail.cf) is adequate for most standalone systems. However, if you plan to connect your system to a network, you will have to modify the sendmail.cf file. DIGITAL UNIX provides the mailconfig and mailsetup utilities, which you can use to create mail configuration files. If you prefer to manipulate the configuration file manually, Digital recommends that you use the m4 macros provided for this purpose. (See the sendmail.m4 reference page.) For more information on configuring mail, see the Network Administra- tion manual. RELATED INFORMATION Commands: dxmail(1X), mail(1), mailconfig(8X), mailsetup(8), mailx(1), Mail(1), sendmail(8) Files: sendmail.cf(4) sendmail.m4(8), Network Administration Standard for the Format of ARPA Internet Text Messages (RFC 822) The Domain Naming Convention for Internet User Applications (RFC 819) UNIX System Administration Handbook, Englewood Cliffs, N.J.: Prentice Hall, Inc., 1989. delim off mail_intro(7)