444 lines
19 KiB
Groff
444 lines
19 KiB
Groff
The stable Postfix release is called postfix-2.2.x where 2=major
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release number, 2=minor release number, x=patchlevel. The stable
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release never changes except for patches that address bugs or
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emergencies. Patches change the patchlevel and the release date.
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New features are developed in snapshot releases. These are called
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postfix-2.3-yyyymmdd where yyyymmdd is the release date (yyyy=year,
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mm=month, dd=day). Patches are never issued for snapshot releases;
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instead, a new snapshot is released.
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The mail_release_date configuration parameter (format: yyyymmdd)
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specifies the release date of a stable release or snapshot release.
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Main changes with Postfix version 2.2
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-------------------------------------
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This is a summary of the changes. These and more are detailed in
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the following sections of this document.
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- TLS and IPv6 support are now built into Postfix, based on code
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from third-party patches.
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- Extended query interface for LDAP, MySQL and PostgreSQL with free
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form SQL queries, and domain filters to reduce unnecessary lookups.
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- SMTP client-side connection reuse. This can dramatically speed
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up deliveries to high-volume destinations that have some servers
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that respond, and some non-responding mail servers.
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- By default, Postfix no longer rewrites message headers in mail
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from remote clients. This includes masquerading, canonical mapping,
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replacing "!" and "%" by "@", and appending the local domain to
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incomplete addresses. Thus, spam from poorly written software no
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longer looks like it came from a local user.
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- When your machine does not have its own domain name, Postfix can
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now replace your "home network" email address by your ISP account
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in outgoing SMTP mail, while leaving your email address unchanged
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when sending mail to someone on the local machine.
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- Compatibility workarounds: you can now selectively turn off ESMTP
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features such as AUTH or STARTTLS in the Postfix SMTP client or
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server, without having to "dumb down" other mail deliveries, and
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without having to use transport maps for outgoing mail.
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- Remote SMTP client resource control (the anvil server). This
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allows you to limit the number of connections, or the number of
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MAIL FROM and RCPT TO commands that an SMTP client can send per
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unit time.
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- Support for CDB, SDBM and NIS+ databases is now built into Postfix
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(but the CDB and SDBM libraries are not).
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- New SMTP access control features, and more.
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Major changes - critical
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------------------------
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BEFORE upgrading from an older release you MUST stop Postfix, unless
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you're running a Postfix 2.2 snapshot release that already has
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Postfix 2.2 IPV6 and TLS support.
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AFTER upgrading from an older release DO NOT copy the old
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master.cf/main.cf files over the new files. Instead, you MUST let
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the Postfix installation procedure update the existing configuration
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files with new service entries.
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[Incompat 20041118] The master-child protocol has changed. The
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Postfix master daemon will log warnings about partial status updates
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if you don't stop and start Postfix.
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[Incompat 20041023, 20041009] The queue manager to delivery agent
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protocol has changed. Mail will remain queued if you do not restart
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the queue manager.
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[Incompat 20050111] The upgrade procedure adds the tlsmgr service
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to the master.cf file. This service entry is not compatible with
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the Postfix/TLS patch.
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[Feature 20040919] The upgrade procedure adds the discard service
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to the master.cf file.
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[Feature 20040720] The upgrade procedure adds the scache (shared
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connection cache) service to the master.cf file.
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Major changes - IPv6 support
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----------------------------
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[Feature 20050111] Postfix version 2.2 IP version 6 support based
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on the Postfix/IPv6 patch by Dean Strik and others. IPv6 support
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is always compiled into Postfix on systems that have Postfix
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compatible IPv6 support. On other systems Postfix will simply use
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IP version 4 just like it did before. See the IPV6_README document
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for what systems are supported, and how to turn on IPv6 in main.cf.
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[Incompat 20050111] Postfix version 2.2 IPv6 support differs from
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the Postfix/IPv6 patch by Dean Strik in a few minor ways.
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- Network protocol support including DNS lookup is selected with
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the inet_protocols parameter instead of the inet_interfaces parameter.
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This is needed so that Postfix will not attempt to deliver mail via
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IPv6 when the system has no IPv6 connectivity.
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- The lmtp_bind_address6 feature was omitted. The Postfix LMTP
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client will be absorbed into the SMTP client, so there is no reason
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to keep adding features to the LMTP client.
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- The CIDR-based address matching code was rewritten. The new
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behavior is believed to be closer to expectation. The results may
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be incompatible with that of the Postfix/IPv6 patch.
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[Incompat 20050117] The Postfix SMTP server now requires that IPv6
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addresses in SMTP commands are specified as [ipv6:ipv6address], as
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described in RFC 2821.
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Major changes - TLS support
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---------------------------
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[Feature 20041210] Postfix version 2.2 TLS support, based on the
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Postfix/TLS patch by Lutz Jaenicke. TLS support is not compiled
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in by default. For more information about Postfix 2.2 TLS support,
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see the TLS_README document.
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[Incompat 20041210] Postfix version 2.2 TLS support differs from
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the Postfix/TLS patch by Lutz Jaenicke in a few minor ways.
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- main.cf: Use btree instead of sdbm for TLS session cache databases.
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Session caches are now accessed only by the tlsmgr(8) process,
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so there are no concurrency issues. Although Postfix still has
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an SDBM client, the SDBM library (1000 lines of code) is no longer
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included with Postfix.
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TLS session caches can use any database that can store objects
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of several kbytes or more, and that implements the sequence
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operation. In most cases, btree databases should be adequate.
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NOTE: You cannot use dbm databases. TLS session objects are too
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large.
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- master.cf: Specify unix instead of fifo for the tlsmgr service type.
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This change is automatically made by the Postfix upgrade procedure.
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The smtp(8) and smtpd(8) processes use a client-server protocol
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in order to access the tlsmgr(8)'s pseudo-random number generation
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(PRNG) pool, and in order to access the TLS session cache databases.
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Such a protocol cannot be run across fifos.
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[Feature 20050209] The Postfix SMTP server policy delegation protocol
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now supplies TLS client certificate information after successful
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verification. The new policy delegation protocol attribute names
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are ccert_subject, ccert_issuer and ccert_fingerprint.
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[Feature 20050208] New "check_ccert_maps maptype:mapname" feature
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to enforce access control based on hexadecimal client certificate
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fingerprints.
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Major changes - SMTP client connection cache
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--------------------------------------------
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[Feature 20040720] SMTP client-side connection caching. Instead of
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disconnecting immediately after a mail transaction, the Postfix
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SMTP client can save the open connection to the scache(8) connection
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cache daemon, so that any SMTP client process can reuse that session
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for another mail transaction. See the CONNECTION_CACHE_README
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document for a description of configuration and implementation.
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This feature introduces the scache (connection cache) server, which
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is added to your master.cf file when you upgrade Postfix.
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[Feature 20040729] Opportunistic SMTP connection caching. When a
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destination has a high volume of mail in the active queue, SMTP
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connection caching is enabled automatically. This is controlled
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with a new configuration parameter "smtp_connection_cache_on_demand"
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(default: yes).
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[Feature 20040723] Per-destination SMTP connection caching. This
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is enabled with the smtp_connection_cache_destinations parameter.
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The parameter requires "bare" domain names or IP addresses without
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"[]" or TCP port, to avoid a syntax conflict between host:port and
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maptype:mapname entries.
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[Feature 20040721] The scache(8) connection cache manager logs cache
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hit and miss statistics every $connection_cache_status_update_time
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seconds (default: 600s). It reports the hit and miss rates for
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lookups by domain, as well as for lookups by network address.
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Major changes - address rewriting
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---------------------------------
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[Feature 20050206] Support for address rewriting in outgoing SMTP
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mail (headers and envelopes). This is useful for sites that have a
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fantasy Internet domain name such as localdomain.local. Mail
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addresses that use fantasy domain names are often rejected by mail
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servers.
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The smtp_generic_maps feature allows you to replace a local mail
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address (user@localdomain.local) by a valid Internet address
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(account@isp.example) when mail is sent across the Internet. The
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feature has no effect on mail that is sent between accounts on the
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local machine. The syntax is described in generic(5) and a detailed
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example is in the STANDARD_CONFIGURATION_README document, the section
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titled "Postfix on hosts without a real Internet hostname".
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[Feature 20041023] By default, Postfix no longer rewrites message
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headers in mail from remote clients. This includes masquerading,
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canonical mapping, replacing "!" and "%" by "@", and appending the
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local domain to incomplete addresses. Thus, spam from poorly written
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software no longer looks like it came from a local user.
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By default, Postfix rewrites message header addresses only when the
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client IP address matches the local machine's interface addresses,
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or when mail is submitted with the Postfix sendmail(1) command.
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Postfix rewrites message headers in mail from other clients only
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when the remote_header_rewrite_domain parameter specifies a domain
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name (such as "domain.invalid"); this domain is appended to incomplete
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addresses. Rewriting also includes masquerading, canonical mapping,
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and replacing "!" and "%" by "@".
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To get the behavior before Postfix 2.2 (always append Postfix's own
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domain to incomplete addresses in message headers, always subject
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message headers to canonical mapping, address masquerading, and
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always replace "!" and "%" by "@") specify:
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/etc/postfix/main.cf:
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local_header_rewrite_clients = static:all
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If you must rewrite headers in mail from specific clients then you
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can specify, for example,
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/etc/postfix/main.cf:
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local_header_rewrite_clients = permit_mynetworks,
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permit_sasl_authenticated, permit_tls_clientcerts,
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check_address_map hash:/etc/postfix/pop-before-smtp
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Postfix always appends local domain information to envelope addresses
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(as opposed to header addresses), because an unqualified envelope
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address is effectively local for the purpose of delivery, and for
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the purpose of replying to it.
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Full details are given in ADDRESS_REWRITING_README, and in the
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postconf(5) manual. For best results, point your browser at the
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ADDRESS_REWRITING_README.html file and navigate to the section
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titled " To rewrite message headers or not, or to label as invalid".
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[Incompat 20050212] When header address rewriting is enabled, Postfix
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now updates a message header only when at least one address in that
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header is modified. Older Postfix versions first parse and then
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un-parse a header so that there may be subtle changes in formatting,
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such as the amount of whitespace between tokens.
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[Incompat 20050227] Postfix no longer changes message header labels.
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Thus, FROM: or CC: are no longer replaced by From: or Cc:.
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[Feature 20040827] Finer control over canonical mapping with
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canonical_classes, sender_canonical_classes and
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recipient_canonical_classes. These specify one or more of
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envelope_sender, header_sender, envelope_recipient or header_recipient.
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The default settings are backwards compatible.
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Major changes - SMTP compatibility controls
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-------------------------------------------
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[Feature 20041218] Fine control for SMTP inter-operability problems,
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by discarding keywords that are sent or received with the EHLO
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handshake. Typically one would discard "pipelining", "starttls",
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or "auth" to work around systems with a broken implementation.
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Specify a list of EHLO keywords with the smtp(d)_discard_ehlo_keywords
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parameters, or specify one or more lookup tables, indexed by remote
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network address, with the smtp(d)_discard_ehlo_keyword_address_maps
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parameters.
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Note: this feature only discards words from the EHLO conversation;
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it does not turn off the actual features in the SMTP server.
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Major changes - database support
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--------------------------------
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[Feature 20050209] Extended LDAP, MySQL and PgSQL query interface
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with free form SQL queries, the domain filter optimization that was
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already available with LDAP and more. This code was worked on by
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many people but Victor Duchovni took the lead. See the respective
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{LDAP,MYSQL,PGSQL}_README and {ldap,mysql,pgsql}_table documents.
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[Feature 20041210] You can now dump an entire database with the new
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postmap/postalias "-s" option. This works only for database types
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with Postfix sequence operator support: hash, btree, dbm, and sdbm.
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[Feature 20041208] Support for CDB databases by Michael Tokarev.
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This supports both Michael's tinycdb and Daniel Bernstein's cdb
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implementations, but neither of the two implementations is bundled
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with Postfix.
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[Feature 20041023] The NIS+ client by Geoff Gibbs is now part of
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the Postfix source tree. Details are given in the nisplus_table(5)
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manual page.
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[Feature 20040827] Easier use of the proxymap(8) service with the
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virtual(8) delivery agent. The virtual(8) delivery agent will
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silently open maps directly when those maps can't be proxied for
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security reasons. This means you can now specify "virtual_mailbox_maps
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= proxy:mysql:whatever" without triggering a fatal error in the
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virtual(8) delivery agent.
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Major changes - remote SMTP client resource control
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---------------------------------------------------
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[Incompat 20041009] The smtpd_client_connection_limit_exceptions
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parameter is renamed to smtpd_client_event_limit_exceptions. Besides
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connections it now also applies to per-client message rate and
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recipient rate limits.
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[Feature 20041009] Per SMTP client message rate and recipient rate
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limits. These limit the number of MAIL FROM or RCPT TO requests
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regardless of whether or not Postfix would have accepted them
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otherwise. The user interface (smtpd_client_message_rate_limit and
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smtpd_client_recipient_rate_limit) is similar to that of the existing
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per SMTP client connection rate limit, and the same warnings apply:
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these features are to be used to stop abuse, and must not be used
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to regulate legitimate mail. More details can be found in the
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postconf(5) manual.
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Major changes - remote SMTP client access control
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-------------------------------------------------
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[Feature 20050209] The Postfix SMTP server policy delegation protocol
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now supplies TLS client certificate information after successful
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verification. The new policy delegation protocol attribute names
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are ccert_subject, ccert_issuer and ccert_fingerprint.
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[Feature 20050208] New "check_ccert_maps maptype:mapname" feature
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to enforce access control based on hexadecimal client certificate
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fingerprints.
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[Feature 20050203] New "permit_inet_interfaces" access restriction
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to allow access from local IP addresses only. This is used for the
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default, purist, setting of local_header_rewrite_clients (rewrite
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only headers in mail from this machine).
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[Feature 20050203] New "sleep time-in-seconds" pseudo access
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restriction to block zombie clients with reject_unauthorized_pipelining
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before the Postfix SMTP server sends the SMTP greeting. See postconf(5)
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for example. This feature is not available the stable Postfix 2.2
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release, but it is documented here so that it will not get lost.
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[Feature 20041118] New "smtpd_end_of_data_restrictions" feature
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that is invoked after the client terminates the SMTP DATA command.
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The syntax is the same as with "smtpd_data_restrictions". In the
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SMTPD policy delegation request, the message size is the actual
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byte count of the message content, instead of the message size
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announced by the client in the MAIL FROM command.
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Major changes - SASL authentication
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-----------------------------------
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[Feature 20040827] Better SMTP client control over the use of SASL
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mechanisms. New smtp_sasl_mechanism_filter mechanism to shorten the
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list of SASL mechanisms from a remote server to just those that the
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local SASL library can actually use.
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Major changes - header/body patterns
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------------------------------------
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[Feature 20050205] REPLACE action in header_checks and body_checks,
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to replace a message header or body line. See header_checks(5) for
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details.
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Major changes - local delivery
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------------------------------
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[Feature 20040621] Control over the working directory when executing
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an external command. With the pipe(8) mailer, specify directory=pathname,
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and with local(8) specify "command_execution_directory = expression"
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where "expression" is subject to $home etc. macro expansion. The
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result of macro expansion is restricted by the set of characters
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specified with execution_directory_expansion_filter.
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Major changes - mail delivery attributes
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----------------------------------------
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[Feature 20041218] More client attributes for delivery to command
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with the local(8) and pipe(8) delivery agents: client_hostname,
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client_address, client_protocol, client_helo, sasl_method, sasl_sender,
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and sasl_username. With local(8), attribute names must be specified
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in upper case.
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Major changes - package creation
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--------------------------------
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[Feature 20050203] To create a ready-to-install package for
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distribution to other systems you can now use "make package" or
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"make non-interactive-package", instead of invoking the internal
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postfix-install script by hand. See the PACKAGE_README file for
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details.
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Major changes - performance
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---------------------------
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[Incompat 20050117] Only the deferred and defer queue directories
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are now hashed by default, instead of eight queue directories. This
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may speed up Postfix boot time on low-traffic systems without
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compromising performance under high load too much. Hashing must be
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turned on for the defer and deferred queue directories, because
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those directories contain lots of files when undeliverable mail is
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backing up.
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[Incompat 20040720] The default SMTP/LMTP timeouts for sending RSET
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are reduced to 20s.
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Major changes - miscellaneous
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-----------------------------
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[Feature 20050203] Safety: Postfix no longer tries to send mail to
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the fallback_relay when the local machine is MX host for the mail
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destination. See the postconf(5) description of the fallback_relay
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feature for details.
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[Incompat 20041023] Support for the non-standard Errors-To: return
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addresses is now removed from Postfix. It was already disabled by
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default with Postfix version 2.1. Since Errors-To: is non-standard,
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there was no guarantee that it would have the desired effect with
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other MTAs.
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[Feature 20040919] A new discard(8) mail delivery agent that makes
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throwing away mail easier and more efficient. It's the Postfix
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equivalent of /dev/null for mail deliveries. On the mail receiving
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side, Postfix already has a /dev/null equivalent in the form of the
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DISCARD action in access maps and header_body_checks.
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[Feature 20040919] Access control for local mail submission, for
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listing the queue, and for flushing the queue. These features are
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controlled with authorized_submit_users, authorized_mailq_users,
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and with authorized_flush_users, respectively. The last two controls
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are always permitted for the super-user and for the mail system
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owner. More information is in the postconf(5) manual.
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[Incompat 20040829] When no recipients are specified on the command
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line or via the -t option, the Postfix sendmail command terminates
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with status EX_USAGE and produces an error message instead of
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accepting the mail first and bouncing it later. This gives more
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direct feedback in case of a common client configuration error.
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