Configuration of Qmail

Qmail is similar to postfix in that it was designed as a sendmail replacement and is a collection of smaller programs instead of one large one. The design goal behind Qmail is security, so often the smaller programs will run as lower-privileged users. Some of the more common Qmail programs are listed in Table 17-2.

Table 17-2. Qmail programs

Program name

Description

tcpserver

Listens for incoming TCP connections and hands them off to the appropriate program. Similar to inetd or xinetd.

qmail-smtpd

Handles incoming email.

qmail-inject

Injects outgoing email into the mail queue.

qmail-send

Delivers mail messages currently in the queue.

qmail-queue

Formats mail correctly and places it in the queue for delivery.

qmail-lspawn

Invokes qmail-local to handle local delivery.

qmail-rspawn

Invokes qmail-remote to handle remote delivery.

qmail-local

Delivers email locally.

qmail-remote

Delivers email remotely.

qmail-qmqpd

Receives mail via the Quick Mail Queueing Protocol and invokes qmail-queue to put mail in the outgoing queue.

qmail-qstat

Summarizes the current contents of the mail queue.

qmail-qread

Lists messages and recipients of emails in the outgoing queue.

qmail-tcpto

Lists hosts that have timed out on mail delivery attempts.

qmail-tcpok

Clears the host timeout list.

qmail-showctl

Analyzes the current qmail configuration files and explains the setup.

qmail-start

A wrapper program that starts qmail-send, qmail-lspawn, qmail-rspawn, and qmail-clean with the appropriate user IDs so mail delivery ...

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