ADDRESS_CLASS_README.html revision 1.1
1 1.1 tron <!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 1.1 tron "http://www.w3.org/TR/html4/loose.dtd"> 3 1.1 tron 4 1.1 tron <html> 5 1.1 tron 6 1.1 tron <head> 7 1.1 tron 8 1.1 tron <title>Postfix Address Classes </title> 9 1.1 tron 10 1.1 tron <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> 11 1.1 tron 12 1.1 tron </head> 13 1.1 tron 14 1.1 tron <body> 15 1.1 tron 16 1.1 tron <h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix Address Classes </h1> 17 1.1 tron 18 1.1 tron <hr> 19 1.1 tron 20 1.1 tron <h2>Introduction</h2> 21 1.1 tron 22 1.1 tron <p> Postfix version 2.0 introduces the concept of address classes. 23 1.1 tron This is a way of grouping recipient addresses by their delivery 24 1.1 tron method. The idea comes from discussions with Victor Duchovni. 25 1.1 tron Although address classes introduced a few incompatibilities they 26 1.1 tron also made it possible to improve the handling of hosted domains 27 1.1 tron and of unknown recipients. </p> 28 1.1 tron 29 1.1 tron <p> This document provides information on the following topics: </p> 30 1.1 tron 31 1.1 tron <ul> 32 1.1 tron 33 1.1 tron <li><a href="#wtf">What are address classes good for?</a> 34 1.1 tron 35 1.1 tron <li><a href="#classes">What address classes does Postfix implement?</a> 36 1.1 tron 37 1.1 tron <li><a href="#improvements">Improvements compared to Postfix 1.1</a> 38 1.1 tron 39 1.1 tron <li><a href="#incompatibility">Incompatibilities with Postfix 1.1</a> 40 1.1 tron 41 1.1 tron </ul> 42 1.1 tron 43 1.1 tron <h2><a name="wtf">What are address classes good for?</a></h2> 44 1.1 tron 45 1.1 tron <p> Why should you care about address classes? This is how Postfix 46 1.1 tron decides what mail to accept, and how to deliver it. In other words, 47 1.1 tron address classes are very important for the operation of Postfix. </p> 48 1.1 tron 49 1.1 tron <p> An address class is defined by three items. </p> 50 1.1 tron 51 1.1 tron <ul> 52 1.1 tron 53 1.1 tron <li> <p> The list of domains that are a member of the class: for 54 1.1 tron example, all local domains, or all relay domains. </p> 55 1.1 tron 56 1.1 tron <li> <p> The default delivery transport. For example, the local, 57 1.1 tron virtual or relay delivery transport (delivery transports are defined 58 1.1 tron in master.cf). This helps to keep Postfix configurations simple, 59 1.1 tron by avoiding the need for explicit routing information in transport 60 1.1 tron maps. </p> 61 1.1 tron 62 1.1 tron <li> <p> The list of valid recipient addresses for that address 63 1.1 tron class. The Postfix SMTP server rejects invalid recipients with 64 1.1 tron "User unknown in <name of address class here> table". This 65 1.1 tron helps to keep the Postfix queue free of undeliverable MAILER-DAEMON 66 1.1 tron messages. </p> 67 1.1 tron 68 1.1 tron </ul> 69 1.1 tron 70 1.1 tron <h2><a name="classes">What address classes does Postfix implement?</a></h2> 71 1.1 tron 72 1.1 tron <p> Initially the list of address classes is hard coded, but this 73 1.1 tron is meant to become extensible. The summary below describes the main 74 1.1 tron purpose of each class, and what the relevant configuration parameters 75 1.1 tron are. </p> 76 1.1 tron 77 1.1 tron <p> The <a name="local_domain_class">local </a> domain class. </p> 78 1.1 tron 79 1.1 tron <ul> 80 1.1 tron 81 1.1 tron <li> <p> Purpose: final delivery for traditional UNIX system accounts 82 1.1 tron and traditional Sendmail-style aliases. This is typically used for 83 1.1 tron the canonical domains of the machine. For a discussion of the 84 1.1 tron difference between canonical domains, hosted domains and other 85 1.1 tron domains, see the VIRTUAL_README file. </p> 86 1.1 tron 87 1.1 tron <li> <p> Domain names are listed with the mydestination parameter. 88 1.1 tron This domain class also includes mail for <i>user@[ipaddress]</i> 89 1.1 tron when the IP address is listed with the inet_interfaces or 90 1.1 tron proxy_interfaces parameters. </p> 91 1.1 tron 92 1.1 tron <li> <p> Valid recipient addresses are listed with the local_recipient_maps 93 1.1 tron parameter, as described in LOCAL_RECIPIENT_README. The Postfix SMTP 94 1.1 tron server rejects invalid recipients with "User unknown in local 95 1.1 tron recipient table". If the local_recipient_maps parameter value is 96 1.1 tron empty, then the Postfix SMTP server accepts any address in the 97 1.1 tron local domain class. </p> 98 1.1 tron 99 1.1 tron <li> <p> The mail delivery transport is specified with the 100 1.1 tron local_transport parameter. The default value is <b>local:$myhostname</b> 101 1.1 tron for delivery with the local(8) delivery agent. </p> 102 1.1 tron 103 1.1 tron </ul> 104 1.1 tron 105 1.1 tron <p> The <a name="virtual_alias_class">virtual alias </a> domain 106 1.1 tron class. </p> 107 1.1 tron 108 1.1 tron <ul> 109 1.1 tron 110 1.1 tron <li> <p> Purpose: hosted domains where each recipient address is 111 1.1 tron aliased to a local UNIX system account or to a remote address. A 112 1.1 tron virtual alias example is given in the VIRTUAL_README file. </p> 113 1.1 tron 114 1.1 tron <li> <p> Domain names are listed in virtual_alias_domains. The 115 1.1 tron default value is $virtual_alias_maps for Postfix 1.1 compatibility. 116 1.1 tron </p> 117 1.1 tron 118 1.1 tron <li> <p> Valid recipient addresses are listed with the virtual_alias_maps 119 1.1 tron parameter. The Postfix SMTP server rejects invalid recipients with 120 1.1 tron "User unknown in virtual alias table". The default value is 121 1.1 tron $virtual_maps for Postfix 1.1 compatibility. </p> 122 1.1 tron 123 1.1 tron <li> <p> There is no mail delivery transport parameter. Every 124 1.1 tron address must be aliased to some other address. </p> 125 1.1 tron 126 1.1 tron </ul> 127 1.1 tron 128 1.1 tron <p> The <a name="virtual_mailbox_class">virtual mailbox </a> domain 129 1.1 tron class. </p> 130 1.1 tron 131 1.1 tron <ul> 132 1.1 tron 133 1.1 tron <li> <p> Purpose: final delivery for hosted domains where each 134 1.1 tron recipient address can have its own mailbox, and where users do not 135 1.1 tron need to have a UNIX system account. A virtual mailbox example is 136 1.1 tron given in the VIRTUAL_README file. </p> 137 1.1 tron 138 1.1 tron <li> <p> Domain names are listed with the virtual_mailbox_domains 139 1.1 tron parameter. The default value is $virtual_mailbox_maps for Postfix 140 1.1 tron 1.1 compatibility. </p> 141 1.1 tron 142 1.1 tron <li> <p> Valid recipient addresses are listed with the virtual_mailbox_maps 143 1.1 tron parameter. The Postfix SMTP server rejects invalid recipients with 144 1.1 tron "User unknown in virtual mailbox table". If this parameter value 145 1.1 tron is empty, the Postfix SMTP server accepts all recipients for domains 146 1.1 tron listed in $virtual_mailbox_domains. </p> 147 1.1 tron 148 1.1 tron <li> <p> The mail delivery transport is specified with the 149 1.1 tron virtual_transport parameter. The default value is <b>virtual</b> 150 1.1 tron for delivery with the virtual(8) delivery agent. </p> 151 1.1 tron 152 1.1 tron </ul> 153 1.1 tron 154 1.1 tron <p> The <a name="relay_domain_class">relay </a> domain class. </p> 155 1.1 tron 156 1.1 tron <ul> 157 1.1 tron 158 1.1 tron <li> <p> Purpose: mail forwarding to remote destinations that list 159 1.1 tron your system as primary or backup MX host. For a discussion of the 160 1.1 tron basic configuration details, see the BASIC_CONFIGURATION_README 161 1.1 tron document. For a discussion of the difference between canonical 162 1.1 tron domains, hosted domains and other domains, see the VIRTUAL_README 163 1.1 tron file. </p> 164 1.1 tron 165 1.1 tron <li> <p> Domain names are listed with the relay_domains parameter. 166 1.1 tron </p> 167 1.1 tron 168 1.1 tron <li> <p> Valid recipient addresses are listed with the relay_recipient_maps 169 1.1 tron parameter. The Postfix SMTP server rejects invalid recipients with 170 1.1 tron "User unknown in relay recipient table". If this parameter value 171 1.1 tron is empty, the Postfix SMTP server accepts all recipients for domains 172 1.1 tron listed with the relay_domains parameter. </p> 173 1.1 tron 174 1.1 tron <li> <p> The mail delivery transport is specified with the 175 1.1 tron relay_transport parameter. The default value is <b>relay</b> which 176 1.1 tron is a clone of the smtp(8) delivery agent. </p> 177 1.1 tron 178 1.1 tron </ul> 179 1.1 tron 180 1.1 tron <p> The <a name="default_domain_class">default </a> domain class. 181 1.1 tron </p> 182 1.1 tron 183 1.1 tron <ul> 184 1.1 tron 185 1.1 tron <li> <p> Purpose: mail forwarding to the Internet on behalf of 186 1.1 tron authorized clients. For a discussion of the basic configuration 187 1.1 tron details, see the BASIC_CONFIGURATION_README file. For a discussion 188 1.1 tron of the difference between canonical domains, hosted domains and 189 1.1 tron other domains, see the VIRTUAL_README file. </p> 190 1.1 tron 191 1.1 tron <li> <p> This class has no destination domain table. </p> 192 1.1 tron 193 1.1 tron <li> <p> This class has no valid recipient address table. </p> 194 1.1 tron 195 1.1 tron <li> <p> The mail delivery transport is specified with the 196 1.1 tron default_transport parameter. The default value is <b>smtp</b> for 197 1.1 tron delivery with the smtp(8) delivery agent. </p> 198 1.1 tron 199 1.1 tron </ul> 200 1.1 tron 201 1.1 tron <h2><a name="improvements">Improvements compared to Postfix 202 1.1 tron 1.1</a></h2> 203 1.1 tron 204 1.1 tron <p> Postfix 2.0 address classes made the following improvements 205 1.1 tron possible over earlier Postfix versions: </p> 206 1.1 tron 207 1.1 tron <ul> 208 1.1 tron 209 1.1 tron <li> <p> You no longer need to specify all the virtual(8) mailbox 210 1.1 tron domains in the Postfix transport map. The virtual(8) delivery agent 211 1.1 tron has become a first-class citizen just like local(8) or smtp(8). 212 1.1 tron </p> 213 1.1 tron 214 1.1 tron <li> <p> On mail gateway systems, address classes provide separation 215 1.1 tron of inbound mail relay traffic ($relay_transport) from outbound 216 1.1 tron traffic ($default_transport). This eliminates a problem where 217 1.1 tron inbound mail deliveries could become resource starved in the presence 218 1.1 tron of a high volume of outbound mail. </p> 219 1.1 tron 220 1.1 tron <li> <p> The SMTP server rejects unknown recipients in a more 221 1.1 tron consistent manner than was possible with Postfix version 1. This 222 1.1 tron is needed to keep undeliverable mail (and bounced undeliverable 223 1.1 tron mail) out of the mail queue. This is controlled by the 224 1.1 tron smtpd_reject_unlisted_recipient configuration parameter. </p> 225 1.1 tron 226 1.1 tron <li> <p> As of Postfix version 2.1, the SMTP server also rejects 227 1.1 tron unknown sender addresses (i.e. addresses that it would reject as 228 1.1 tron unknown recipient addresses). Sender "egress filtering" can help 229 1.1 tron to slow down an email worm explosion. This is controlled by the 230 1.1 tron smtpd_reject_unlisted_sender configuration parameter. </p> 231 1.1 tron 232 1.1 tron </ul> 233 1.1 tron 234 1.1 tron <h2><a name="incompatibility">Incompatibilities with Postfix 1.1</a></h2> 235 1.1 tron 236 1.1 tron <p> Postfix 2.0 address classes introduce a few incompatible changes 237 1.1 tron in documented behavior. In order to ease the transitions, new 238 1.1 tron parameters have default values that are backwards compatible. </p> 239 1.1 tron 240 1.1 tron <ul> 241 1.1 tron 242 1.1 tron <li> <p> The virtual_maps parameter is replaced by virtual_alias_maps 243 1.1 tron (for address lookups) and by virtual_alias_domains (for the names 244 1.1 tron of what were formerly called "Postfix-style virtual domains"). </p> 245 1.1 tron 246 1.1 tron <p> For backwards compatibility with Postfix version 1.1, the new 247 1.1 tron virtual_alias_maps parameter defaults to $virtual_maps, and the 248 1.1 tron new virtual_alias_domains parameter defaults to $virtual_alias_maps. 249 1.1 tron </p> 250 1.1 tron 251 1.1 tron <li> <p> The virtual_mailbox_maps parameter now has a companion 252 1.1 tron parameter called virtual_mailbox_domains (for the names of domains 253 1.1 tron served by the virtual delivery agent). The virtual_mailbox_maps 254 1.1 tron parameter is now used for address lookups only. </p> 255 1.1 tron 256 1.1 tron <p> For backwards compatibility with Postfix version 1.1, the new 257 1.1 tron virtual_mailbox_domains parameter defaults to $virtual_mailbox_maps. 258 1.1 tron </p> 259 1.1 tron 260 1.1 tron <li> <p> Introduction of the relay_recipient_maps parameter. The 261 1.1 tron Postfix SMTP server can use this to block mail for relay recipients 262 1.1 tron that don't exist. This list is empty by default, which means accept 263 1.1 tron any recipient. </p> 264 1.1 tron 265 1.1 tron <li> <p> The local_recipient_maps feature is now turned on by 266 1.1 tron default. The Postfix SMTP server uses this to reject mail for 267 1.1 tron unknown local recipients. See the LOCAL_RECIPIENT_README file hints 268 1.1 tron and tips. </p> 269 1.1 tron 270 1.1 tron <li> <p> Introduction of the relay delivery transport in master.cf. 271 1.1 tron This helps to avoid mail delivery scheduling problems on inbound 272 1.1 tron mail relays when there is a lot of outbound mail, but may require 273 1.1 tron that you update your "defer_transports" setting. </p> 274 1.1 tron 275 1.1 tron </ul> 276 1.1 tron 277 1.1 tron </body> 278 1.1 tron 279 1.1 tron </html> 280
Indexes created Fri Jun 26 00:24:39 UTC 2026