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diff --git a/proto/ADDRESS_CLASS_README.html b/proto/ADDRESS_CLASS_README.html new file mode 100644 index 0000000..ca4bb67 --- /dev/null +++ b/proto/ADDRESS_CLASS_README.html @@ -0,0 +1,279 @@ +<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" + "http://www.w3.org/TR/html4/loose.dtd"> + +<html> + +<head> + +<title>Postfix Address Classes </title> + +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> + +</head> + +<body> + +<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix Address Classes </h1> + +<hr> + +<h2>Introduction</h2> + +<p> Postfix version 2.0 introduces the concept of address classes. +This is a way of grouping recipient addresses by their delivery +method. The idea comes from discussions with Victor Duchovni. +Although address classes introduced a few incompatibilities they +also made it possible to improve the handling of hosted domains +and of unknown recipients. </p> + +<p> This document provides information on the following topics: </p> + +<ul> + +<li><a href="#wtf">What are address classes good for?</a> + +<li><a href="#classes">What address classes does Postfix implement?</a> + +<li><a href="#improvements">Improvements compared to Postfix 1.1</a> + +<li><a href="#incompatibility">Incompatibilities with Postfix 1.1</a> + +</ul> + +<h2><a name="wtf">What are address classes good for?</a></h2> + +<p> Why should you care about address classes? This is how Postfix +decides what mail to accept, and how to deliver it. In other words, +address classes are very important for the operation of Postfix. </p> + +<p> An address class is defined by three items. </p> + +<ul> + +<li> <p> The list of domains that are a member of the class: for +example, all local domains, or all relay domains. </p> + +<li> <p> The default delivery transport. For example, the local, +virtual or relay delivery transport (delivery transports are defined +in master.cf). This helps to keep Postfix configurations simple, +by avoiding the need for explicit routing information in transport +maps. </p> + +<li> <p> The list of valid recipient addresses for that address +class. The Postfix SMTP server rejects invalid recipients with +"User unknown in <name of address class here> table". This +helps to keep the Postfix queue free of undeliverable MAILER-DAEMON +messages. </p> + +</ul> + +<h2><a name="classes">What address classes does Postfix implement?</a></h2> + +<p> Initially the list of address classes is hard coded, but this +is meant to become extensible. The summary below describes the main +purpose of each class, and what the relevant configuration parameters +are. </p> + +<p> The <a name="local_domain_class">local </a> domain class. </p> + +<ul> + +<li> <p> Purpose: final delivery for traditional UNIX system accounts +and traditional Sendmail-style aliases. This is typically used for +the canonical domains of the machine. For a discussion of the +difference between canonical domains, hosted domains and other +domains, see the VIRTUAL_README file. </p> + +<li> <p> Domain names are listed with the mydestination parameter. +This domain class also includes mail for <i>user@[ipaddress]</i> +when the IP address is listed with the inet_interfaces or +proxy_interfaces parameters. </p> + +<li> <p> Valid recipient addresses are listed with the local_recipient_maps +parameter, as described in LOCAL_RECIPIENT_README. The Postfix SMTP +server rejects invalid recipients with "User unknown in local +recipient table". If the local_recipient_maps parameter value is +empty, then the Postfix SMTP server accepts any address in the +local domain class. </p> + +<li> <p> The mail delivery transport is specified with the +local_transport parameter. The default value is <b>local:$myhostname</b> +for delivery with the local(8) delivery agent. </p> + +</ul> + +<p> The <a name="virtual_alias_class">virtual alias </a> domain +class. </p> + +<ul> + +<li> <p> Purpose: hosted domains where each recipient address is +aliased to a local UNIX system account or to a remote address. A +virtual alias example is given in the VIRTUAL_README file. </p> + +<li> <p> Domain names are listed in virtual_alias_domains. The +default value is $virtual_alias_maps for Postfix 1.1 compatibility. +</p> + +<li> <p> Valid recipient addresses are listed with the virtual_alias_maps +parameter. The Postfix SMTP server rejects invalid recipients with +"User unknown in virtual alias table". The default value is +$virtual_maps for Postfix 1.1 compatibility. </p> + +<li> <p> There is no mail delivery transport parameter. Every +address must be aliased to some other address. </p> + +</ul> + +<p> The <a name="virtual_mailbox_class">virtual mailbox </a> domain +class. </p> + +<ul> + +<li> <p> Purpose: final delivery for hosted domains where each +recipient address can have its own mailbox, and where users do not +need to have a UNIX system account. A virtual mailbox example is +given in the VIRTUAL_README file. </p> + +<li> <p> Domain names are listed with the virtual_mailbox_domains +parameter. The default value is $virtual_mailbox_maps for Postfix +1.1 compatibility. </p> + +<li> <p> Valid recipient addresses are listed with the virtual_mailbox_maps +parameter. The Postfix SMTP server rejects invalid recipients with +"User unknown in virtual mailbox table". If this parameter value +is empty, the Postfix SMTP server accepts all recipients for domains +listed in $virtual_mailbox_domains. </p> + +<li> <p> The mail delivery transport is specified with the +virtual_transport parameter. The default value is <b>virtual</b> +for delivery with the virtual(8) delivery agent. </p> + +</ul> + +<p> The <a name="relay_domain_class">relay </a> domain class. </p> + +<ul> + +<li> <p> Purpose: mail forwarding to remote destinations that list +your system as primary or backup MX host. For a discussion of the +basic configuration details, see the BASIC_CONFIGURATION_README +document. For a discussion of the difference between canonical +domains, hosted domains and other domains, see the VIRTUAL_README +file. </p> + +<li> <p> Domain names are listed with the relay_domains parameter. +</p> + +<li> <p> Valid recipient addresses are listed with the relay_recipient_maps +parameter. The Postfix SMTP server rejects invalid recipients with +"User unknown in relay recipient table". If this parameter value +is empty, the Postfix SMTP server accepts all recipients for domains +listed with the relay_domains parameter. </p> + +<li> <p> The mail delivery transport is specified with the +relay_transport parameter. The default value is <b>relay</b> which +is a clone of the smtp(8) delivery agent. </p> + +</ul> + +<p> The <a name="default_domain_class">default </a> domain class. +</p> + +<ul> + +<li> <p> Purpose: mail forwarding to the Internet on behalf of +authorized clients. For a discussion of the basic configuration +details, see the BASIC_CONFIGURATION_README file. For a discussion +of the difference between canonical domains, hosted domains and +other domains, see the VIRTUAL_README file. </p> + +<li> <p> This class has no destination domain table. </p> + +<li> <p> This class has no valid recipient address table. </p> + +<li> <p> The mail delivery transport is specified with the +default_transport parameter. The default value is <b>smtp</b> for +delivery with the smtp(8) delivery agent. </p> + +</ul> + +<h2><a name="improvements">Improvements compared to Postfix +1.1</a></h2> + +<p> Postfix 2.0 address classes made the following improvements +possible over earlier Postfix versions: </p> + +<ul> + +<li> <p> You no longer need to specify all the virtual(8) mailbox +domains in the Postfix transport map. The virtual(8) delivery agent +has become a first-class citizen just like local(8) or smtp(8). +</p> + +<li> <p> On mail gateway systems, address classes provide separation +of inbound mail relay traffic ($relay_transport) from outbound +traffic ($default_transport). This eliminates a problem where +inbound mail deliveries could become resource starved in the presence +of a high volume of outbound mail. </p> + +<li> <p> The SMTP server rejects unknown recipients in a more +consistent manner than was possible with Postfix version 1. This +is needed to keep undeliverable mail (and bounced undeliverable +mail) out of the mail queue. This is controlled by the +smtpd_reject_unlisted_recipient configuration parameter. </p> + +<li> <p> As of Postfix version 2.1, the SMTP server also rejects +unknown sender addresses (i.e. addresses that it would reject as +unknown recipient addresses). Sender "egress filtering" can help +to slow down an email worm explosion. This is controlled by the +smtpd_reject_unlisted_sender configuration parameter. </p> + +</ul> + +<h2><a name="incompatibility">Incompatibilities with Postfix 1.1</a></h2> + +<p> Postfix 2.0 address classes introduce a few incompatible changes +in documented behavior. In order to ease the transitions, new +parameters have default values that are backwards compatible. </p> + +<ul> + +<li> <p> The virtual_maps parameter is replaced by virtual_alias_maps +(for address lookups) and by virtual_alias_domains (for the names +of what were formerly called "Postfix-style virtual domains"). </p> + +<p> For backwards compatibility with Postfix version 1.1, the new +virtual_alias_maps parameter defaults to $virtual_maps, and the +new virtual_alias_domains parameter defaults to $virtual_alias_maps. +</p> + +<li> <p> The virtual_mailbox_maps parameter now has a companion +parameter called virtual_mailbox_domains (for the names of domains +served by the virtual delivery agent). The virtual_mailbox_maps +parameter is now used for address lookups only. </p> + +<p> For backwards compatibility with Postfix version 1.1, the new +virtual_mailbox_domains parameter defaults to $virtual_mailbox_maps. +</p> + +<li> <p> Introduction of the relay_recipient_maps parameter. The +Postfix SMTP server can use this to block mail for relay recipients +that don't exist. This list is empty by default, which means accept +any recipient. </p> + +<li> <p> The local_recipient_maps feature is now turned on by +default. The Postfix SMTP server uses this to reject mail for +unknown local recipients. See the LOCAL_RECIPIENT_README file hints +and tips. </p> + +<li> <p> Introduction of the relay delivery transport in master.cf. +This helps to avoid mail delivery scheduling problems on inbound +mail relays when there is a lot of outbound mail, but may require +that you update your "defer_transports" setting. </p> + +</ul> + +</body> + +</html> |