.\" Copyright (c) 2005, 2006 Sendmail, Inc. and its suppliers.
.\"	 All rights reserved.
.\"
.\" $Id: meta1.8,v 1.2 2006/10/29 04:06:10 ca Exp $
.\"
.TH META1 8 "$Date: 2006/10/29 04:06:10 $
.SH NAME
meta1 
\- Message Transfer Agent
.SH DESCRIPTION
meta1 is a Message Transfer Agent, which implements the
Simple Mail Transfer Protocol (SMTP)
as specified by RFC 2821
and various extensions, e.g.,
STARTTLS,
AUTH,
PIPELINING,
as well as other protocols, e.g.,
LMTP.
.PP
meta1 is a modularized message transfer agent consisting of
five (or more) persistent processes,
four of which are multi-threaded.
A central queue manager
.BI QMGR
controls SMTP servers
.BI SMTPS
and SMTP clients
.BI SMTPC
to receive and send e-mails,
an address resolver
.BI SMAR
provides lookups in
various maps including DNS for mail routing,
and a main control program
.BI MCP
starts the others processes
and watches over their execution.
The queue manager organizes the flow of messages through the system
and provides measures to avoid overloading the local or remote systems
by implementing a central control instance.
.PP
Incoming messages are accepted by an SMTP server
which stores the messages in the content database
.BI (CDB) .
The envelope information, i.e., sender and recipients,
is stored by the queue manager in an incoming queue
.BI (IQDB)
and written to disk to the incoming queue backup database
.BI (IBDB).
For a delivery, the envelope information must be transferred into
the active queue
.BI (AQ).
The scheduler in QMGR takes recipient envelopes from AQ
and creates transactions which are given to an SMTP client
for delivery.
An SMTP client takes the transaction information and tries to
send a message whose content is read from CDB.
After a successful delivery attempt a record is written to IBDB
that logs this information.
The deferred envelope database
.BI (DEFEDB)
is only used if a message cannot be delivered during the first attempt.
.SH FILES
All files are specified in a configuration files
which must be given as argument to
.B mcp .
.\"/etc/smx/smx.conf
.SH SEE ALSO
mail(1),
procmail(1),
meta1.conf(5),
mcp(8),
qmgr(8),
smar(8),
smtpc(8),
smtps(8).
.PP
DARPA
Internet Request for Comments 
.IR RFC2033 ,
.IR RFC2487 ,
.IR RFC2554 ,
.IR RFC2821 ,
.IR RFC2920 .
.PP
.IR "meta1 README"
.SH HISTORY
MeTA1 is a successor of sendmail X.
.\".SH BUGS
.\"This version of meta1 does not come with
.\"a local delivery agent
.\"nor a mail submission program.