Adding upstream version 3.5.24.upstream/3.5.24 upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
author: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-27 12:06:34 +0000
committer: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-27 12:06:34 +0000
commit: 5e61585d76ae77fd5e9e96ebabb57afa4d74880d (patch)
tree: 2b467823aaeebc7ef8bc9e3cabe8074eaef1666d /proto/SMTPUTF8_README.html
parent: Initial commit. (diff)
download: postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.tar.xz
postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.zip
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+<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
+        "http://www.w3.org/TR/html4/loose.dtd">
+
+<html>
+
+<head>
+
+<title>Postfix SMTPUTF8 support</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 SMTPUTF8 support
+</h1>
+
+<hr>
+
+<h2> Overview </h2>
+
+<p> This document describes Postfix support for Email Address
+Internationalization (EAI) as defined in RFC 6531 (SMTPUTF8 extension),
+RFC 6532 (Internationalized email headers) and RFC 6533 (Internationalized
+delivery status notifications). Introduced with Postfix version
+3.0, this fully supports UTF-8 email addresses and UTF-8 message
+header values. </p>
+
+<p> Topics covered in this document: </p>
+
+<ul> 
+
+<li><a href="#building">Building with/without SMTPUTF8 support</a>
+
+<li><a href="#enabling">Enabling Postfix SMTPUTF8 support</a>
+
+<li><a href="#using">Using Postfix SMTPUTF8 support</a>
+
+<li><a href="#detecting">SMTPUTF8 autodetection</a>
+
+<li><a href="#limitations">Limitations of the current implementation</a>
+
+<li><a href="#compatibility">Compatibility with pre-SMTPUTF8 environments</a>
+
+<li><a href="#idna2003">Compatibility with IDNA2003</a>
+
+<li><a href="#credits">Credits</a>
+
+</ul>
+
+<h2> <a name="building">Building Postfix with/without SMTPUTF8 support</a> </h2>
+
+<p> Postfix will build with SMTPUTF8 support if the ICU version
+&ge; 46 library and header files are installed on the system.  The
+package name varies with the OS distribution. The table shows package
+names for a number of platforms at the time this text was written.
+</p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th> OS Distribution </th> <th> Package </th> </tr>
+
+<tr> <td> FreeBSD, NetBSD, etc. </td> <td> icu </td> </tr>
+
+<tr> <td> Centos, Fedora, RHEL </td> <td> libicu-devel </td> </tr>
+
+<tr> <td> Debian, Ubuntu </td> <td> libicu-dev </td> </tr>
+
+</table>
+
+</blockquote>
+
+<p> To force Postfix to build without SMTPUTF8, specify: </p>
+
+<blockquote>
+<pre>
+$ <b>make makefiles CCARGS="-DNO_EAI ..."</b>
+</pre>
+</blockquote>
+
+<p> See the INSTALL document for more "make makefiles" options. </p>
+
+<h2> <a name="enabling">Enabling Postfix SMTPUTF8 support</a> </h2>
+
+<p> There is more to SMTPUTF8 than just Postfix itself. The rest
+of your email infrastructure also needs to be able to handle UTF-8
+email addresses and message header values. This includes SMTPUTF8
+protocol support in SMTP-based content filters (Amavisd), LMTP
+servers (Dovecot), and down-stream SMTP servers. </p>
+
+<p> Postfix SMTPUTF8 support is enabled by default, but it may be
+disabled as part of a backwards-compatibility safety net (see the
+COMPATIBILITY_README file). </p>
+
+<p> SMTPUTF8 support is enabled by setting the smtputf8_enable
+parameter in main.cf:</p>
+
+<blockquote>
+<pre>
+# <b>postconf "smtputf8_enable = yes"</b>
+# <b>postfix reload</b>
+</pre>
+</blockquote>
+
+<p> (With Postfix &le; 3.1, you may also need to specify "<b>option_group
+= client</b>" in Postfix MySQL client files, to enable UTF8 support
+in MySQL queries. This setting is the default as of Postfix 3.2.) </p>
+
+<p> With SMTPUTF8 support enabled, Postfix changes behavior with
+respect to earlier Postfix releases: </p>
+
+<ul>
+
+<li> <p> UTF-8 is permitted in the myorigin parameter value. However,
+the myhostname and mydomain parameters must currently specify
+ASCII-only domain names. This limitation may be removed later. </p>
+
+<li> <p> UTF-8 is the only form of non-ASCII text that Postfix
+supports in access tables, address rewriting tables, and other
+tables that are indexed with an email address, hostname, or domain
+name. </p>
+
+<li> <p> The header_checks-like and body_checks-like features are
+not UTF-8 enabled, and therefore they do not enforce UTF-8 syntax
+rules on inputs and outputs.  The reason is that non-ASCII text may
+be sent in encodings other than UTF-8, and that real email sometimes
+contains malformed headers.  Instead of skipping non-UTF-8 content,
+Postfix should be able to filter it.  You may try to enable UTF-8
+processing by starting a PCRE pattern with the sequence (*UTF8),
+but this is will result in "message not accepted, try again later"
+errors when the PCRE pattern matcher encounters non-UTF-8 input.
+Other features that are not UTF-8 enabled are smtpd_command_filter,
+smtp_reply_filter, the *_delivery_status_filter features, and the
+*_dns_reply_filter features (the latter because DNS is by definition
+an ASCII protocol).  </p>
+
+<li> <p> The Postfix SMTP server announces SMTPUTF8 support in the
+EHLO response. </p>
+
+<pre>
+220 server.example.com ESMTP Postfix
+<b>EHLO client.example.com</b>
+250-server.example.com
+250-PIPELINING
+250-SIZE 10240000
+250-VRFY
+250-ETRN
+250-STARTTLS
+250-AUTH PLAIN LOGIN
+250-ENHANCEDSTATUSCODES
+250-8BITMIME
+250-DSN
+250 SMTPUTF8
+</pre>
+
+<li> <p> The Postfix SMTP server accepts the SMTPUTF8 request in
+MAIL FROM and VRFY commands. </p>
+
+<pre>
+<b>MAIL FROM:&lt;address&gt; SMTPUTF8 ...</b>
+
+<b>VRFY address SMTPUTF8</b>
+</pre>
+
+<li> <p> The Postfix SMTP client may issue the SMTPUTF8 request in
+MAIL FROM commands. </p>
+
+<li> <p> The Postfix SMTP server accepts UTF-8 in email address
+domains, but only after the remote SMTP client issues the
+SMTPUTF8 request in MAIL FROM or VRFY commands.  </p>
+
+</ul>
+
+<p> Postfix already permitted UTF-8 in message header values
+and in address localparts. This does not change. </p>
+
+<h2> <a name="using">Using Postfix SMTPUTF8 support</a> </h2>
+
+<p> After Postfix SMTPUTF8 support is turned on, Postfix behavior
+will depend on 1) whether a remote SMTP client requests SMTPUTF8
+support, 2) the presence of UTF-8 content in the message envelope
+and headers, and 3) whether a down-stream SMTP (or LMTP) server
+announces SMTPUTF8 support. </p>
+
+<ul>
+
+<li> <p> When the Postfix SMTP server receives a message WITHOUT
+the SMTPUTF8 request, Postfix handles the message as it has always
+done (at least that is the default, see autodetection below).
+Specifically, the Postfix SMTP server does not accept UTF-8 in the
+envelope sender domain name or envelope recipient domain name, and
+the Postfix SMTP client does not issue the SMTPUTF8 request when
+delivering that message to an SMTP or LMTP server that announces
+SMTPUTF8 support (again, that is the default). Postfix will accept
+UTF-8 in message header values and in the localpart of envelope
+sender and recipient addresses, because it has always done that.
+</p>
+
+<li> <p>  When the Postfix SMTP server receives a message WITH the
+SMTPUTF8 request, Postfix will issue the SMTPUTF8 request when
+delivering that message to an SMTP or LMTP server that announces
+SMTPUTF8 support. This is not configurable. </p>
+
+<li> <p>  When a message is received with the SMTPUTF8 request,
+Postfix will deliver the message to a non-SMTPUTF8 SMTP or LMTP
+server ONLY if: </p>
+
+    <ul>
+
+    <li> <p>  No message header value contains UTF-8. </p>
+
+    <li> <p>  The envelope sender address contains no UTF-8, </p>
+
+    <li> <p>  No envelope recipient address for that specific
+    SMTP/LMTP delivery transaction contains UTF-8. </p>
+
+	<blockquote> <p> NOTE: Recipients in other email delivery
+	transactions for that same message may still contain UTF-8.
+	</p> </blockquote>
+
+   </ul>
+
+   <p> Otherwise, Postfix will return the recipient(s) for that
+   email delivery transaction as undeliverable. The delivery status
+   notification message will be an SMTPUTF8 message. It will therefore
+   be subject to the same restrictions as email that is received
+   with the SMTPUTF8 request. </p>
+
+<li> <p>  When the Postfix SMTP server receives a message with the
+SMTPUTF8 request, that request also applies after the message is
+forwarded via a virtual or local alias, or $HOME/.forward file.
+</p>
+
+</ul>
+
+<h2> <a name="detecting">SMTPUTF8 autodetection</a> </h2>
+
+<p> This section applies only to systems that have SMTPUTF8 support
+turned on (smtputf8_enable = yes). </p>
+
+<p> For compatibility with pre-SMTPUTF8 environments, Postfix does
+not automatically set the "SMTPUTF8 requested" flag on messages
+from non-SMTPUTF8 clients that contain an UTF-8 header value or
+UTF-8 address localpart. This would make such messages undeliverable
+to non-SMTPUTF8 servers, and could be a barrier to SMTPUTF8 adoption.
+</p>
+
+<p> By default, Postfix sets the "SMTPUTF8 requested" flag only on
+address verification probes and on Postfix sendmail submissions
+that contain UTF-8 in the sender address, UTF-8 in a recipient
+address, or UTF-8 in a message header value. </p>
+
+<blockquote>
+<pre>
+/etc/postfix/main.cf:
+    smtputf8_autodetect_classes = sendmail, verify
+</pre>
+</blockquote>
+
+<p> However, if you have a non-ASCII myorigin or mydomain setting,
+or if you have a configuration that introduces UTF-8 addresses with
+virtual aliases, canonical mappings, or BCC mappings, then you may
+have to apply SMTPUTF8 autodetection to all email: </p>
+
+<blockquote>
+<pre>
+/etc/postfix/main.cf:
+    smtputf8_autodetect_classes = all
+</pre>
+</blockquote>
+
+<p> This will, of course, also flag email that was received without
+SMTPUTF8 request, but that contains UTF-8 in a sender address
+localpart, receiver address localpart, or message header value.
+Such email was not standards-compliant, but Postfix would have
+delivered it if SMTPUTF8 support was disabled. </p>
+
+<h2> <a name="limitations">Limitations of the current implementation</a>
+</h2>
+
+<p> The Postfix implementation is a work in progress; limitations
+are steadily being removed. The text below describes the situation
+at one point in time. </p>
+
+<h3> No automatic conversions between ASCII and UTF-8 domain names. </h3>
+
+<p> Some background: According to RFC 6530 and related documents,
+an internationalized domain name can appear in two forms: the UTF-8
+form, and the ASCII (xn--mumble) form. An internationalized address
+localpart must be encoded in UTF-8; the RFCs do not define an ASCII
+alternative form. </p>
+
+<p> Postfix currently does not convert internationalized domain
+names from UTF-8 into ASCII (or from ASCII into UTF-8) before using
+domain names in SMTP commands and responses, before looking up
+domain names in lists such as mydestination, relay_domains or in
+lookup tables such as access tables, etc., before using domain names
+in a policy daemon or Milter request, or before logging events.
+</p>
+
+<p> Postfix does, however, casefold domain names and email addresses
+before matching them against a Postfix configuration parameter or 
+lookup table. </p>
+
+<p> In order to use Postfix SMTPUTF8 support: </p>
+
+<ul>
+
+<li> <p> The Postfix parameters myhostname and mydomain must be in
+ASCII form. One is a substring of the other, and the myhostname
+value is used in SMTP commands and responses that require ASCII.
+The parameter myorigin (added to local addresses without domain)
+supports UTF-8.  </p>
+
+<li> <p> You need to configure both the ASCII and UTF-8 forms of
+an Internationalized domain name in Postfix parameters such as
+mydestination and relay_domains, as well as lookup table search
+keys. </p>
+
+<li> <p> Milters, content filters, policy servers and logfile
+analysis tools need to be able to handle both the ASCII and UTF-8
+forms of Internationalized domain names. </p>
+
+</ul>
+
+<h2> <a name="compatibility">Compatibility with pre-SMTPUTF8
+environments</a> </h2>
+
+<h3> Mailing lists with UTF-8 and non-UTF-8 subscribers </h3>
+
+<p> With Postfix, there is no need to split mailing lists into UTF-8 and
+non-UTF-8 members. Postfix will try to deliver the non-UTF8 subscribers
+over "traditional" non-SMTPUTF8 sessions, as long as the message
+has an ASCII envelope sender address and all-ASCII header values.
+The mailing list manager may have to apply RFC 2047 encoding to
+satisfy that last condition. </p>
+
+<h3> Pre-existing non-ASCII email flows </h3>
+
+<p> With "smtputf8_enable = no", Postfix handles email with non-ASCII
+in address localparts (and in headers) as before.  The vast majority
+of email software is perfectly capable of handling such email, even
+if pre-SMTPUTF8 standards do not support such practice. </p>
+
+<h3> Rejecting non-UTF8 addresses </h3>
+
+<p> With "smtputf8_enable = yes", Postfix
+requires that non-ASCII address information is encoded in UTF-8 and
+will reject other encodings such as ISO-8859. It is not practical
+for Postfix to support multiple encodings at the same time.  There
+is no problem with RFC 2047 encodings such as "=?ISO-8859-1?Q?text?=",
+because those use only characters from the ASCII characterset. </p>
+
+<h3> Rejecting non-ASCII addresses in non-SMTPUTF8 transactions </h3>
+
+<p> Setting "strict_smtputf8 = yes" in addition to "smtputf8_enable
+= yes" will enable stricter enforcement of the SMTPUTF8 protocol.
+Specifically, the Postfix SMTP server will not only reject non-UTF8
+sender or recipient addresses, it will in addition accept UTF-8
+sender or recipient addresses only when the client requests an
+SMTPUTF8 mail transaction. </p>
+
+<h2> <a name="idna2003">Compatibility with IDNA2003</a> </h2>
+
+<p> Postfix &ge; 3.2 by default disables the 'transitional'
+compatibility between IDNA2003 and IDNA2008, when converting UTF-8
+domain names to/from the ASCII form that is used in DNS lookups.
+This makes Postfix behavior consistent with current versions of the
+Firefox and Chrome web browsers. Specify "enable_idna2003_compatibility
+= yes" to get the historical behavior. </p>
+
+<p> This affects the conversion of domain names that contain for
+example the German sz (ß) and the Greek zeta (ς). See
+http://unicode.org/cldr/utility/idna.jsp for more examples. </p>
+
+<h2> <a name="credits">Credits</a> </h2>
+
+<ul>
+
+<li> <p> May 15, 2014: Arnt Gulbrandsen posted his patch for Unicode
+email support.  This work was sponsored by CNNIC. </p>
+
+<li> <p> July 15, 2014: Wietse integrated Arnt Gulbrandsen's code
+and released Postfix with SMTPUTF8 support. </p>
+
+<li> <p> January 2015: Wietse added UTF-8 support for casefolding
+in Postfix lookup tables and caseless string comparison in Postfix
+list-based features. </p>
+
+</ul>
+
+</body>
+
+</html>
+
author	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-27 12:06:34 +0000
committer	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-27 12:06:34 +0000
commit	5e61585d76ae77fd5e9e96ebabb57afa4d74880d (patch)
tree	2b467823aaeebc7ef8bc9e3cabe8074eaef1666d /proto/SMTPUTF8_README.html
parent	Initial commit. (diff)
download	postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.tar.xz postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.zip