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| -rw-r--r-- | RELEASE_NOTES-2.5 | 376 |
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diff --git a/RELEASE_NOTES-2.5 b/RELEASE_NOTES-2.5 new file mode 100644 index 0000000..f560d3b --- /dev/null +++ b/RELEASE_NOTES-2.5 @@ -0,0 +1,376 @@ +The stable Postfix release is called postfix-2.5.x where 2=major +release number, 5=minor release number, x=patchlevel. The stable +release never changes except for patches that address bugs or +emergencies. Patches change the patchlevel and the release date. + +New features are developed in snapshot releases. These are called +postfix-2.6-yyyymmdd where yyyymmdd is the release date (yyyy=year, +mm=month, dd=day). Patches are never issued for snapshot releases; +instead, a new snapshot is released. + +The mail_release_date configuration parameter (format: yyyymmdd) +specifies the release date of a stable release or snapshot release. + +Incompatibility with Postfix 2.3 and earlier +-------------------------------------------- + +If you upgrade from Postfix 2.3 or earlier, read RELEASE_NOTES-2.4 +before proceeding. + +Major changes - critical +------------------------ + +[Incompat 20071224] The protocol to send Milter information from +smtpd(8) to cleanup(8) processes was cleaned up. If you use the +Milter feature, and upgrade a live Postfix system, you may see an +"unexpected record type" warning from a cleanup(8) server process. +To prevent this, execute the command "postfix reload". The +incompatibility affects only systems that use the Milter feature. +It does not cause loss of mail, just a minor delay until the remote +SMTP client retries. + +[Incompat 20071212] The allow_min_user feature now applies to both +sender and recipient addresses in SMTP commands. With earlier Postfix +versions, only recipients were subject to the allow_min_user feature, +and the restriction took effect at mail delivery time, causing mail +to be bounced later instead of being rejected immediately. + +[Incompat 20071206] The "make install" and "make upgrade" procedures +now create a Postfix-owned directory for Postfix-writable data files +such as caches and random numbers. The location is specified with +the "data_directory" parameter (default: "/var/lib/postfix"), and +the ownership is specified with the "mail_owner" parameter. + +[Incompat 20071206] The tlsmgr(8) and verify(8) servers no longer +use root privileges when opening the address_verify_map, +*_tls_session_cache_database, and tls_random_exchange_name cache +files. This avoids a potential security loophole where the ownership +of a file (or directory) does not match the trust level of the +content of that file (or directory). + +[Incompat 20071206] The tlsmgr(8) and verify(8) cache files should +now be stored as Postfix-owned files under the Postfix-owned +data_directory. As a migration aid, attempts to open these files +under a non-Postfix directory are redirected to the Postfix-owned +data_directory, and a warning is logged. + +This is an example of the warning messages: + + Dec 6 12:56:22 bristle postfix/tlsmgr[7899]: warning: request + to update file /etc/postfix/prng_exch in non-postfix directory + /etc/postfix + + Dec 6 12:56:22 bristle postfix/tlsmgr[7899]: warning: redirecting + the request to postfix-owned data_directory /var/lib/postfix + +If you wish to continue using a pre-existing tls_random_exchange_name +or address_verify_map file, move it to the Postfix-owned data_directory +and change ownership from root to Postfix (that is, change ownership +to the account specified with the mail_owner configuration parameter). + +[Feature 20071205] The "make install" and "make upgrade" procedures +now create a Postfix-owned directory for Postfix-writable data files +such as caches and random numbers. The location is specified with +the "data_directory" parameter (default: "/var/lib/postfix"), and +the ownership is specified with the "mail_owner" parameter. + +[Incompat 20071203] The "make upgrade" procedure adds a new service +"proxywrite" to the master.cf file, for read/write lookup table +access. If you copy your old configuration file over the updated +one, you may see warnings in the maillog file like this: + + connect #xx to subsystem private/proxywrite: No such file or directory + +To recover, run "postfix upgrade-configuration" again. + +[Incompat 20070613] The pipe(8) delivery agent no longer allows +delivery with the same group ID as the main.cf postdrop group. + +Major changes - malware defense +------------------------------- + +[Feature 20080107] New "pass" service type in master.cf. Written +years ago, this allows future front-end daemons to accept all +connections from the network, and to hand over connections from +well-behaved clients to Postfix. Since this feature uses file +descriptor passing, it imposes no overhead once a connection is +handed over to Postfix. See master(5) for a few details. + +[Feature 20070911] Stress-adaptive behavior. When a "public" network +service runs into an "all processes are busy" condition, the master(8) +daemon logs a warning, restarts the service, and runs it with "-o +stress=yes" on the command line (under normal conditions it runs +the service with "-o stress=" on the command line). This can be +used to make main.cf parameter settings stress dependent, for +example: + +/etc/postfix/main.cf: + smtpd_timeout = ${stress?10}${stress:300} + smtpd_hard_error_limit = ${stress?1}${stress:20} + +Translation: under conditions of stress, use an smtpd_timeout value +of 10 seconds instead of 300, and use smtpd_hard_error_limit of 1 +instead of 20. The syntax is explained in the postconf(5) manpage. + +The STRESS_README file gives examples of how to mitigate flooding +problems. + +Major changes - tls support +--------------------------- + +[Incompat 20080109] TLS logging output has changed to make it more +useful. Existing logfile parser regular expressions may need +adjustment. + +- More log entries include the "hostnamename[ipaddress]" of the + remote SMTP peer. + +- Certificate trust chain error reports show only the first + error certificate (closest to the trust chain root), and the + reporting is more human-readable for the most likely errors. + +- After the completion of the TLS handshake, the session is logged + with TLS loglevel >= 1 as either "Untrusted", "Trusted" or + "Verified" (SMTP client only). + - "Untrusted" means that the certificate trust chain is invalid, + or that the root CA is not trusted. + - "Trusted" means that the certificate trust chain is valid, and + that the root CA is trusted. + - "Verified" means that the certificate meets the SMTP client's + matching criteria for the destination: + - In the case of a destination name match, "Verified" also + implies "Trusted". + - In the case of a fingerprint match, CA trust is not applicable. + +- The logging of protocol states with TLS loglevel >= 2 no longer + reports bogus error conditions when OpenSSL asks Postfix to refill + (or flush) network I/O buffers. This loglevel is for debugging + only; use 0 or 1 in production configurations. + +[Feature 20080109] The Postfix SMTP client has a new "fingerprint" +security level. This avoids dependencies on CAs, and relies entirely +on bi-lateral exchange of public keys (really self-signed or private +CA signed X.509 public key certificates). Scalability is clearly +limited. For details, see the fingerprint discussion in TLS_README. + +[Feature 20080109] The Postfix SMTP server can now use SHA1 instead +of MD5 to compute remote SMTP client certificate fingerprints. For +backwards compatibility, the default algorithm is MD5. For details, +see the "smtpd_tls_fingerprint_digest" parameter in the postconf(5) +manual. + +[Feature 20080109] The maximum certificate trust chain depth +(verifydepth) is finally implemented in the Postfix TLS library. +Previously, the parameter had no effect. The default depth was +changed to 9 (the OpenSSL default) for backwards compatibility. + +If you have explicity limited the verification depth in main.cf, +check that the configured limit meets your needs. See the +"lmtp_tls_scert_verifydepth", "smtp_tls_scert_verifydepth" and +"smtpd_tls_ccert_verifydepth" parameters in the postconf(5) manual. + +[Feature 20080109] The selection of SSL/TLS protocols for mandatory +TLS can now use exclusion rather than inclusion. Either form is +acceptable; see the "lmtp_tls_mandatory_protocols", +"smtp_tls_mandatory_protocols" and "smtpd_tls_mandatory_protocols" +parameters in the postconf(5) manual. + +Major changes - scheduler +------------------------- + +[Feature 20071130] Revised queue manager with separate mechanisms +for per-destination concurrency control and for dead destination +detection. The concurrency control supports less-than-1 feedback +to allow for more gradual concurrency adjustments, and uses hysteresis +to avoid rapid oscillations. A destination is declared "dead" after +a configurable number of pseudo-cohorts(*) reports connection or +handshake failure. + +(*) A pseudo-cohort is a number of delivery requests equal to a + destination's delivery concurrency. + +The drawbacks of the old +/-1 feedback scheduler are a) overshoot +due to exponential delivery concurrency growth with each pseudo-cohort(*) +(5-10-20...); b) throttling down to zero concurrency after a single +pseudo-cohort(*) failure. The latter was especially an issue with +low-concurrency channels where a single failure could be sufficient +to mark a destination as "dead", and suspend further deliveries. + +New configuration parameters: destination_concurrency_feedback_debug, +default_destination_concurrency_positive_feedback, +default_destination_concurrency_negative_feedback, +default_destination_concurrency_failed_cohort_limit, as well as +transport-specific versions of the same. + +The default parameter settings are backwards compatible with older +Postfix versions. This may change after better defaults are field +tested. + +The updated SCHEDULER_README document describes the theory behind +the new concurrency scheduler, as well as Patrik Rak's preemptive +job scheduler. See postconf(5) for more extensive descriptions of +the configuration parameters. + +Major changes - small/home office +--------------------------------- + +[Feature 20080115] Preliminary SOHO_README document that combines +bits and pieces from other document in one place, so that it is +easier to find. This document describes the "mail sending" side +only. + +[Feature 20071202] Output rate control in the queue manager. For +example, specify "smtp_destination_rate_delay = 5m", to pause five +minutes between message deliveries. More information in the postconf(5) +manual under "default_destination_rate_delay". + +Major changes - smtp client +--------------------------- + +[Incompat 20080114] The Postfix SMTP client now by default defers +mail after a remote SMTP server rejects a SASL authentication +attempt. Specify "smtp_sasl_auth_soft_bounce = no" for the old +behavior. + +[Feature 20080114] The Postfix SMTP client can now avoid making +repeated SASL login failures with the same server, username and +password. To enable this safety feature, specify for example +"smtp_sasl_auth_cache_name = proxy:btree:/var/lib/postfix/sasl_auth_cache" +(access through the proxy service is required). Instead of trying +to SASL authenticate, the Postfix SMTP client defers or bounces +mail as controlled with the new smtp_sasl_auth_soft_bounce configuration +parameter. + +[Feature 20071111] Header/body checks are now available in the SMTP +client, after the implementation was moved from the cleanup server +to a library module. The SMTP client provides only actions that +don't change the message delivery time or destination: warn, replace, +prepend, ignore, dunno, ok. + +[Incompat 20070614] By default, the Postfix Cyrus SASL client no +longer sends a SASL authoriZation ID (authzid); it sends only the +SASL authentiCation ID (authcid) plus the authcid's password. Specify +"send_cyrus_sasl_authzid = yes" to get the old behavior. + +Major changes - smtp server +--------------------------- + +[Feature 20070724] Not really major. New support for RFC 3848 +(Received: headers with ESMTPS, ESMTPA, or ESMTPSA); updated SASL +support according to RFC 4954, resulting in small changes to SMTP +reply codes and (DSN) enhanced status codes. + +Major changes - milter +---------------------- + +[Incompat 20071224] The protocol to send Milter information from +smtpd(8) to cleanup(8) processes was cleaned up. If you use the +Milter feature, and upgrade a live Postfix system, you may see an +"unexpected record type" warning from a cleanup(8) server process. +To prevent this, execute the command "postfix reload". The +incompatibility affects only systems that use the Milter feature. +It does not cause loss of mail, just a minor delay until the remote +SMTP client retries. + +[Feature 20071221] Support for most of the Sendmail 8.14 Milter +protocol features. + +To enable the new features specify "milter_protocol = 6" and link +the filter application with a libmilter library from Sendmail 8.14 +or later. + +Sendmail 8.14 Milter features supported at this time: + +- NR_CONN, NR_HELO, NR_MAIL, NR_RCPT, NR_DATA, NR_UNKN, NR_HDR, + NR_EOH, NR_BODY: The filter can tell Postfix that it won't reply + to some of the SMTP events that Postfix sends. This makes the + protocol less chatty and improves performance. + +- SKIP: The filter can tell Postfix to skip sending the rest of + the message body, which also improves performance. + +- HDR_LEADSPC: The filter can request that Postfix does not delete + the first space character between header name and header value + when sending a header to the filter, and that Postfix does not + insert a space character between header name and header value + when receiving a header from the filter. This fixes a limitation + in the old Milter protocol that can break DKIM and DK signatures. + +- SETSYMLIST: The filter can override one or more of the main.cf + milter_xxx_macros parameter settings. + +Sendmail 8.14 Milter features not supported at this time: + +- RCPT_REJ: report rejected recipients to the mail filter. + +- CHGFROM: replace sender, with optional ESMTP command parameters. + +- ADDRCPT_PAR: add recipient, with optional ESMTP command parameters. + +It is unclear when (if ever) the missing features will be implemented. +SMFIP_RCPT_REJ requires invasive changes in the SMTP server recipient +processing and error handling. SMFIR_CHGFROM and SMFIR_ADDRCPT_PAR +require ESMTP command-line parsing in the cleanup server. Unfortunately, +Sendmail's documentation does not specify what ESMTP options are +supported, but only discusses examples of things that don't work. + +Major changes - address verification +------------------------------------ + +[Incompat 20070514] The default sender address for address verification +probes was changed from "postmaster" to "double-bounce", so that +the Postfix SMTP server no longer causes surprising behavior by +excluding "postmaster" from SMTP server access controls. + +Major changes - ldap +-------------------- + +[Incompat 20071216] Due to an incompatible API change between +OpenLDAP 2.0.11 and 2.0.12, an LDAP client compiled for OpenLDAP +version <= 2.0.11 will refuse to work with an OpenLDAP library +version >= 2.0.12 and vice versa. + +Major changes - logging +----------------------- + +[Incompat 20080109] TLS logging output has changed to make it more +useful. Existing logfile parser regular expressions may need +adjustment. + +- More log entries include the "hostnamename[ipaddress]" of the + remote SMTP peer. + +- Certificate trust chain error reports show only the first + error certificate (closest to the trust chain root), and the + reporting is more human-readable for the most likely errors. + +- After the completion of the TLS handshake, the session is logged + with TLS loglevel >= 1 as either "Untrusted", "Trusted" or + "Verified" (SMTP client only). + - "Untrusted" means that the certificate trust chain is invalid, + or that the root CA is not trusted. + - "Trusted" means that the certificate trust chain is valid, and + that the root CA is trusted. + - "Verified" means that the certificate meets the SMTP client's + matching criteria for the destination: + - In the case of a destination name match, "Verified" also + implies "Trusted". + - In the case of a fingerprint match, CA trust is not applicable. + +- The logging of protocol states with TLS loglevel >= 2 no longer + reports bogus error conditions when OpenSSL asks Postfix to refill + (or flush) network I/O buffers. This loglevel is for debugging + only; use 0 or 1 in production configurations. + +[Incompat 20071216] The SMTP "transcript of session" email now +includes the remote SMTP server TCP port number. + +Major changes - loop detection +------------------------------ + +[Incompat 20070422] [Incompat 20070422] When the pipe(8) delivery +agent is configured to create the optional Delivered-To: header, +it now first checks if that same header is already present in the +message. If so, the message is returned as undeliverable. This test +should have been included with Postfix 2.0 when Delivered-To: support +was added to the pipe(8) delivery agent. |