The stable Postfix release is called postfix-2.8.x where 2=major release number, 8=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-2.9-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. If you upgrade from Postfix 2.6 or earlier, read RELEASE_NOTES-2.7 before proceeding. Major changes - restart Postfix ------------------------------- If you upgrade from Postfix 2.6 or earlier, you must execute "postfix stop" and "postfix start" before you can use the postscreen(8) daemon. This is needed because the Postfix 2.6 "pass" master service type did not work reliably on some systems. If you upgrade from Postfix 2.7, or from Postfix 2.8 before July 25, 2010, you must execute "postfix reload" (or "postfix stop" followed by "postfix start"). This is needed because the queue manager to delivery agent protocol has changed. Failure to do this results in repeated logging of warnings with: warning: unexpected attribute rewrite_context ... If the warning does not go away after restarting Postfix, examine the output from this command: strings -af /usr/libexec/postfix/* | grep mail_version= (where /usr/libexec/postfix is the value of main.cf:daemon_directory) and update the executables that have a version string that differs from the other programs. Major changes - DNSBL/DNSWL support ----------------------------------- [Feature 20101126] Support for address patterns in DNS blacklist and whitelist lookup results. For example, "reject_rbl_client example.com=127.0.0.[2;4;6..8]" will reject clients when the lookup result is 127.0.0.2, 127.0.0.4, 127.0.0.6, 127.0.0.7, or 127.0.0.8. The setting "postscreen_dnsbl_sites = example.com=127.0.0.[2;4;6..8]" rejects the same clients. An IPv4 address pattern has four fields separated by ".". Each field is either a decimal number, or a sequence inside "" that contains one or more ";"-separated decimal numbers or number..number ranges. Thus, any pattern field can be a sequence inside "", but a "" sequence cannot span multiple address fields, and a pattern field cannot contain both a number and a "" sequence at the same time. This means that the pattern 1.2.[3.4] is not valid (the sequence [3.4] cannot span two address fields) and the pattern 18.104.22.168[6..9] is also not valid (the last field cannot be both number 3 and sequence [6..9] at the same time). The syntax for IPv4 patterns is as follows: v4pattern = v4field "." v4field "." v4field "." v4field v4field = v4octet | "[" v4sequence "]" v4octet = any decimal number in the range 0 through 255 v4sequence = v4seq_member | v4sequence ";" v4seq_member v4seq_member = v4octet | v4octet ".." v4octet [Feature 20101105] The Postfix SMTP server now supports DNS-based whitelisting with several safety features: permit_dnswl_client whitelists a client by IP address, and permit_rhswl_client whitelists a client by its hostname. These features use the same syntax as reject_rbl_client and reject_rhsbl_client, respectively. The main difference is that they return PERMIT instead of REJECT. Whitelisting is primarily a tool to reduce the false positive rate of DNS blocklist lookups. Client name whitelisting should not be used to make exceptions to access rules. The reason is that client name lookup can fail unpredictably due to some temporary outage. For safety reasons, permit_dnswl_client and permit_rhswl_client are silently ignored when they would override reject_unauth_destination. Also for safety reasons, the result is DEFER_IF_REJECT when DNS whitelist lookup fails (this result will be made configurable). Major changes - sqlite support ------------------------------ [Feature 20100617] Support for read-only sqlite database access, with code by Axel Steiner and documentation by Jesus Garcia Crespo. See SQLITE_README and sqlite_table(5) for details. Major changes - Milter support ------------------------------- [Incompat 20101103] Postfix now requests default delivery status notifications when adding a recipient with the Milter smfi_addrcpt action, instead of "never notify" as with Postfix automatically-added recipients (always_bcc and sender/recipient_bcc_maps). Major changes - alias expansion ------------------------------- [Incompat 20101202] Postfix now reports a temporary delivery error when the result of virtual alias expansion would exceed the virtual_alias_recursion_limit or virtual_alias_expansion_limit. Previously, Postfix would silently drop the excess recipients and deliver the message. [Incompat 20101006] To avoid repeated delivery to mailing lists with pathological nested alias configurations, the local(8) delivery agent now keeps the owner-alias attribute of a parent alias, when delivering mail to a child alias that does not have its own owner alias. With this change, local addresses from that child alias will be written to a new queue file, and a temporary error with one local address will no longer result in repeated delivery to other mailing list members. Specify "reset_owner_alias = yes" for the older, more fragile, behavior. The postconf(5) manpage entry for "reset_owner_alias" has more background information on this issue. Major changes - dns lookup -------------------------- [Incompat 20100827] The Postfix SMTP client no longer appends the local domain when looking up a DNS name without ".". Specify "smtp_dns_resolver_options = res_defnames" to get the old behavior, which may produce unexpected results. Major changes - logging ----------------------- [Incompat 20100728] The format of the "postfix/smtpd[pid]: queueid: client=host[addr]" logfile record has changed. When available, the before-filter client information and the before-filter queue ID are now appended to the end of the record. [Feature 20100728] Improved message tracking across SMTP-based content filters. The logging example below is from an after-filter SMTP server. Here, 951F692462F is a before-filter queue ID, hades.porcupine.org is a before-filter SMTP client, while 6B4A9924782 is the after-filter queue ID, and localhost[127.0.0.1] is the SMTP-based content filter that sends mail into the after-filter SMTP server. postfix/smtpd: 6B4A9924782: client=localhost[127.0.0.1], orig_queue_id=951F692462F orig_client=hades.porcupine.org[22.214.171.124] Major changes - reply footer ---------------------------- [Feature 20110105] The SMTP server now supports contact information that is appended to "reject" responses. This includes SMTP server responses that aren't logged to the maillog file, such as responses to syntax errors, or unsupported commands. Example: smtpd_reject_footer = For assistance, call 800-555-0101. Server response: 550-5.5.1 <user@example> Recipient address rejected: User unknown 550 5.5.1 For assistance, call 800-555-0101. This feature supports macro expansion ($client_address, $localtime, etc.), as documented in the postconf(5) manpage. This feature is also supported as postscreen_reject_footer using the same setting as smtpd_reject_footer by default. Major changes - rfc compliance ------------------------------ [Incompat 20101206] Postfix by default no longer adds a "To: undisclosed-recipients:;" header when no recipient specified in the message header. The Internet mail RFCs have supported messages without recipient header for almost 10 years now. For backwards compatibility, specify: /etc/postfix/main.cf undisclosed_recipients_header = To: undisclosed-recipients:; Note: both the ":" and ";" are required. Major changes - tls support --------------------------- [Incompat 20110102] The Postfix SMTP server now always re-computes the SASL mechanism list after successful completion of the STARTTLS command. Earlier versions only re-computed the mechanism list when the values of smtp_sasl_tls_security_options and smtp_sasl_security_options differ. This could produce incorrect results, because the Dovecot authentication server may change responses when the SMTP session is encrypted. [Incompat 20110102] The smtpd_starttls_timeout default value is now stress-dependent. By default, TLS negotiations must now complete under overload in 10s instead of 300s. [Feature 20101223] The new tls_disable_workarounds parameter specifies a list or bit-mask of OpenSSL bug work-arounds to disable. This may be necessary if one of the work-arounds enabled by default in OpenSSL proves to pose a security risk, or introduces an unexpected interoperability issue. Some bug work-arounds known to be problematic are disabled in the default value of the parameter when linked with an OpenSSL library that could be vulnerable. See postconf(5) and TLS_README for details. With "tls_preempt_cipherlist = yes" the Postfix SMTP server will choose its most preferred cipher that is supported (offered) by the client. This can lead to a more secure or performant cipher choice, but may also introduce interoperability problems when a client announces support for a cipher that does not work. See postconf(5) and TLS_README for details. [Feature 20101217] The lower-level code in the TLS engine was simplified by removing an unnecessary layer of data copying. OpenSSL now writes directly to the network. The difference in performance should be hardly noticeable. [Incompat 20100610] Postfix no longer appends the system-supplied default CA certificates to the lists specified with *_tls_CAfile or with *_tls_CApath. This prevents third-party certificates from getting mail relay permission with the permit_tls_all_clientcerts feature. Unfortunately this change may cause compatibility problems when configurations rely on certificate verification for other purposes. Specify "tls_append_default_CA = yes" for backwards compatibility. Major changes - postscreen -------------------------- See html/POSTSCREEN_README.html for an introduction to postscreen (or the text version, README_FILES/POSTSCREEN_README). The text below summarizes milestones in reverse chronological order. [Incompat 20110111] The postscreen_access_list feature replaces the postscreen_whitelist_networks and postscreen_blacklist_networks features. Reason: CIDR-style access maps are some 100x faster than the code that implemented the postscreen_white/blacklist_networks support. CIDR maps can match about 100 million CIDR patterns/second on a modern CPU, which is not blindingly fast but adequate for the near future. [Feature 20110102] STARTTLS support for the postscreen(8) daemon. This is implemented by a new tlsproxy(8) daemon that you will need to enable in master.cf (see POSTSCREEN_README for instructions). tlsproxy(8) implements its own tlsproxy_mumble versions of TLS-related smtpd_mumble parameters. This leaves no confusion about which parameters will affect tlsproxy(8) behavior, but it adds another 25 parameters to the documentation. [Incompat 20100912] If your DNSBL queries have a "secret" in the domain name, you must now censor this information from the postscreen(8) SMTP replies. For example: /etc/postfix/main.cf: postscreen_dnsbl_reply_map = texthash:/etc/postfix/dnsbl_reply /etc/postfix/dnsbl_reply: # Secret DNSBL name Name in postscreen(8) replies secret.zen.spamhaus.org zen.spamhaus.org The texthash: format is similar to hash: except that there is no need to run postmap(1) before the file can be used, and that it does not detect changes after the file is read. It is new with Postfix version 2.8. [Incompat 20100912] The postscreen "continue" action is now called "ignore". The old name is still supported but no longer documented. [Incompat 20100912] The postscreen_hangup_action parameter was removed. Postscreen now always behaves as if "postscreen_hangup_action = drop". [Incompat 20100912] The postscreen_cache_retention_time default was increased from 1d to 7d, to avoid deleting results from expensive deep SMTP protocol tests too quickly. [Feature 20100912] SMTP protocol engine for deep protocol tests, and for logging the helo/sender/recipient information when postscreen rejects an attempt to deliver mail. The postscreen SMTP protocol engine implements a number of deep protocol tests and defers or rejects all attempts to deliver mail. The first test detects unauthorized SMTP command pipelining (an SMTP client sends multiple commands, instead of sending one command and waiting for the server response); a second deep protocol test implements the Postfix SMTP server's smtpd_forbidden_commands feature (a client sends commands such as CONNECT, GET, POST); and a third deep protocol test detects spambots that send SMTP commands that end in newline instead of carriage-return/newline. Real spambots rarely make this mistake, but poorly-written software often does. Deep protocol tests are disabled by default, because the built-in SMTP engine cannot not hand off the "live" connection from a good SMTP client to a Postfix SMTP server process. To work around this, postscreen(8) defers attempts to deliver mail with a 4XX status, and waits for the client to disconnect. The next time a good client connects, it will be allowed to talk to a Postfix SMTP server process to deliver mail. [Feature 20100830] Postscreen DNSBL support is extended with optional fixed-string filters, with optional integral weight factors, and with an adjustable threshold to block SMTP clients with DNSBL score >= that threshold. Reply filters will be implemented later. The updated postscreen configuration syntax is: postscreen_dnsbl_sites = domain[=ipaddr][*weight] ... postscreen_dnsbl_threshold = score Elements inside  are optional, ipaddr is an IPv4 address, and weight and score are integral numbers. The  are not part of the postscreen_dnsbl_sites input. By default, weight and score are equal to 1, and entries without filter will match any non-error DNSBL reply. Use a negative weight value for whitelisting. Examples: To use example.com as a high-confidence blocklist, and to block mail with example.net and example.org only when both agree, use: postscreen_dnsbl_threshold = 2 postscreen_dnsbl_sites = example.com*2, example.net, example.org To filter only DNSBL replies containing 127.0.0.4, use: postscreen_dnsbl_sites = example.com=127.0.0.4 See also postconf(5) for the fine details. [Incompat 20100101] When periodic cache cleanup is enabled (the default), the postscreen(8) server now requires that the cache database supports the "delete" and "sequence" operations. To disable periodic cache cleanup specify a zero postscreen_cache_cleanup_interval value. [Feature 20100101] Periodic cache cleanup for the postscreen(8) cache database. The time between cache cleanup runs is controlled with the postscreen_cache_cleanup_interval (default: 12h) parameter. Cache cleanup increases the database access latency, so this should not be run more often than necessary. In addition, the postscreen_cache_retention_time (default: 1d) parameter specifies how long to keep an expired entry in the cache. This prevents a client from being logged as "NEW" after its record expired only a little while ago. [Feature 20091008] Prototype postscreen(8) server that runs a number of time-consuming checks in parallel for all incoming SMTP connections, before clients are allowed to talk to a real Postfix SMTP server. It detects clients that start talking too soon, or clients that appear on DNS blocklists, or clients that hang up without sending any command. By doing these checks in a single postscreen(8) process, Postfix can avoid wasting one SMTP server process per connection. A side benefit of postscreen(8)'s DNSBL lookups is that DNS records are already cached before the Postfix SMTP server looks them up later. postscreen(8) maintains a temporary whitelist of positive decisions. Once an SMTP client is whitelisted, it is immediately forwarded to a real Postfix SMTP server process without further checking. By default, the program logs only statistics, and it does not run any checks on clients in mynetworks (primarily, to avoid problems with buggy SMTP implementations in network appliances). The logging function alone is already useful for research.