SENDMAILX(8)

NAME
sendmailx - Message Transfer System

DESCRIPTION
sendmailx is a Message Transfer System, 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.

sendmail X is a modularized message transfer system consisting of five (or more) persistent processes, four of which are multi-threaded. A central queue manager QMGR controls SMTP servers SMTPS and SMTP clients SMTPC to receive and send e-mails, an address resolver SMAR provides lookups in various maps including DNS for mail routing, and a main control program 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.

Incoming messages are accepted by an SMTP server which stores the messages in the content database (CDB). The envelope information, i.e., sender and recipients, is stored by the queue manager in an incoming queue (IQDB) and written to disk to the incoming queue backup database (IBDB). For a delivery, the envelope information must be transferred into the active queue (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 (DEFEDB) is only used if a message cannot be delivered during the first attempt.

FILES
All files are specified in a configuration files which must be given as argument to mcp .

SEE ALSO
mail(1), procmail(1), sendmailx.conf(5), mcp(8), qmgr(8), smar(8), smtpc(8), smtps(8).

DARPA Internet Request for Comments RFC2033, RFC2487, RFC2554, RFC2821, RFC2920.

Sendmail X README
http://www.sendmail.org/sm-X/