Sun Microsystems Sun Workstation 100U System Manager's Manual page 322

SENDMAIL
'I
line.
The header is formatted
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a series of lines of the form
field-name: field-value
Field-value can be split across lines by startin, the followin, lines with a space or a tab.
Some header fields have special internal meanin" and have appropriate special processin,.
Other headers are simply passed through. Some header fields may be added automatically,
such as time stamps.
The body is a series of text lines. It
is
completely uninterpreted and untouched,
except that lines beginning with a dot have the dot doubled when transmitted over an
SMTP channel. This extra dot is stripped by the receiver.
3.5. Meaaage Delivery
The send queue is ordered by receivin, host before transmission to implement mes-
sage batching. Each address is marked as it is sent so rescanning the list is safe. An argu-
ment list is built as the scan proceeds. Mail to files is detected during the scan of the send
list. The interface to the mailer is performed using one of the techniques described in sec-
tion 2.2.
After a connection is established,
BendmtJil
makes the per-mailer changes to the
header and sends the result to the mailer. II any mail is rejected by the mailer, a lIag is
set to invoke the return-to-sender function after all delivery completes.
3.1. Queued Mesaaga
If the mailer returns a "temporary failure" exit status, the message is queued. A
control file is used to describe the recipients to be sent to and various other parameters.
This control file is formatted as a series of lines, each describing a sender, a recipient, the
time of submission, or some other salient parameter of the message. The header of the
message is stored in the control file, so that the associated data file in the queue is just the
temporary file that was originally collected.
3.7. Configuration
Configuration is controlled primarily by a configuration file read at startup. SendmtJu
should not need to be recomplied except
(1) To change operating systems (V6, V7/32V, 4BSD).
(2) To remove or insert the DBM (UNIX database) library.
(3) To change ARPANET reply codes.
(4) To add headers fields requiring special processing.
Adding mailers or changing parsing (i.e., rewriting) or routing information does not require
recompilation.
If the mail is being sent by a local user, and the file ".mailcr' exists in the sender's
home directory, that file is read as a configuration file arter the system configuration file.
The primary use of this feature is to add header lines.
The configuration file encodes macro definitions, header definitions, mailer definitions,
rewriting rules, and options.
3.7.1. Macro.
Macros can be used in three ways. Certain macros transmit unstructured textual
information into the mail system, such as the name Bfndmoil
will use to identify itself
in error messages. Other macros transmit information from BfndmtJil to the
configuration file for use in creatin, other fields (such
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argument vectors to mailers):
the name of the sender, and the host and user of the recipient. Other macros are
Version 4.1
DRAFT Last Mod 8/1,0/83