This is the Postfix 3.1 (stable) release. The stable Postfix release is called postfix-3.1.x where 3=major release number, 1=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-3.2-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 2.11 or earlier, read RELEASE_NOTES-3.0 before proceeding. TLS Workaround for Postfix 3.4.6, 3.3.5, 3.2.10 and 3.1.13 ----------------------------------------------------------- This release introduces a workaround for implementations that hang Postfix while shutting down a TLS session, until Postfix times out. With "tls_fast_shutdown_enable = yes" (the default), Postfix no longer waits for a remote TLS peer to respond to a TLS 'close' request. This behavior is recommended with TLSv1.0 and later. Specify "tls_fast_shutdown_enable = no" to get historical Postfix behavior. Workaround - UTF8 support in Postfix MySQL queries -------------------------------------------------- Someone reported false "not found" errors with MySQL map queries that contain UTF8-encoded text. To avoid such errors, specify "option_group = client" in Postfix MySQL configuration files. This will be the default setting with Postfix 3.2 and later. Major changes - address verification safety ------------------------------------------- [Feature 20151227] The new address_verify_pending_request_limit parameter introduces a safety limit for the number of address verification probes in the active queue. The default limit is 1/4 of the active queue maximum size. The queue manager enforces the limit by tempfailing probe messages that exceed the limit. This design avoids dependencies on global counters that get out of sync after a process or system crash. Tempfailing verify requests is not as bad as one might think. The Postfix verify cache proactively updates active addresses weeks before they expire. The address_verify_pending_request_limit affects only unknown addresses, and inactive addresses that have expired from the address verify cache (by default, after 31 days). Major changes - json support ---------------------------- [Feature 20151129] Machine-readable, JSON-formatted queue listing with "postqueue -j" (no "mailq" equivalent). The output is a stream of JSON objects, one per queue file. To simplify parsing, each JSON object is formatted as one text line followed by one newline character. See the postqueue(1) manpage for a detailed description of the output format. Major changes - milter support ------------------------------ [Feature 20150523] The milter_macro_defaults feature provides an optional list of macro name=value pairs. These specify default values for Milter macros when no value is available from the SMTP session context. For example, with "milter_macro_defaults = auth_type=TLS", the Postfix SMTP server will send an auth_type of "TLS" to a Milter, unless the remote client authenticates with SASL. This feature was originally implemented for a submission service that may authenticate clients with a TLS certificate, without having to make changes to the code that implements TLS support. Major changes - output rate control ----------------------------------- [Feature 20150710] Destination-independent delivery rate delay Support to enforce a destination-independent delay between email deliveries. The following example inserts 20 seconds of delay between all deliveries with the SMTP transport, limiting the delivery rate to at most three messages per minute. /etc/postfix/ smtp_transport_rate_delay = 20s For details, see the description of default_transport_rate_delay and transport_transport_rate_delay in the postconf(5) manpage. Major changes - postscreen dnsbl -------------------------------- [Feature 20150710] postscreen support for the TTL of DNSBL and DNSWL lookup results Historically, the default setting "postscreen_dnsbl_ttl = 1h" assumes that a "not found" result from a DNSBL server will be valid for one hour. This may have been adequate five years ago when postscreen was first implemented, but nowadays, that one hour can result in missed opportunities to block new spambots. To address this, postscreen now respects the TTL of DNSBL "not found" replies, as well as the TTL of DNSWL replies (both "found" and "not found"). The TTL for a "not found" reply is determined according to RFC 2308 (the TTL of an SOA record in the reply). Support for DNSBL or DNSWL reply TTL values is controlled by two configuration parameters: postscreen_dnsbl_min_ttl (default: 60 seconds). This parameter specifies a minimum for the amount of time that a DNSBL or DNSWL result will be cached in the postscreen_cache_map. This prevents an excessive number of postscreen cache updates when a DNSBL or DNSWL server specifies a very small reply TTL. postscreen_dnsbl_max_ttl (default: $postscreen_dnsbl_ttl or 1 hour) This parameter specifies a maximum for the amount of time that a DNSBL or DNSWL result will be cached in the postscreen_cache_map. This prevents cache pollution when a DNSBL or DNSWL server specifies a very large reply TTL. The postscreen_dnsbl_ttl parameter is now obsolete, and has become the default value for the new postscreen_dnsbl_max_ttl parameter. Major changes - sasl auth safety -------------------------------- [Feature 20151031] New "smtpd_client_auth_rate_limit" feature, to enforce an optional rate limit on AUTH commands per SMTP client IP address. Similar to other smtpd_client_*_rate_limit features, this enforces a limit on the number of requests per $anvil_rate_time_unit. Major changes - smtpd policy ---------------------------- [Feature 20150913] New SMTPD policy service attribute "policy_context", with a corresponding "smtpd_policy_service_policy_context" configuration parameter. Originally, this was implemented to share the same SMTPD policy service endpoint among multiple check_policy_service clients. Major changes - tls ------------------- [Feature 20160207] A new "postfix tls" command to quickly enable opportunistic TLS in the Postfix SMTP client or server, and to manage SMTP server keys and certificates, including certificate signing requests and TLSA DNS records for DANE. See the postfix-tls(1) manpage for a detailed description. [Feature 20160103] The Postfix SMTP client by default enables DANE policies when an MX host has a (DNSSEC) secure TLSA DNS record, even if the MX DNS record was obtained with insecure lookups. The existence of a secure TLSA record implies that the host wants to talk TLS and not plaintext. For details see the smtp_tls_dane_insecure_mx_policy configuration parameter. [Incompat 20150721] As of the middle of 2015, all supported Postfix releases no longer enable "export" grade ciphers for opportunistic TLS, and no longer use the deprecated SSLv2 and SSLv3 protocols for mandatory or opportunistic TLS. These changes are very unlikely to cause problems with server-to-server communication over the Internet, but they may result in interoperability problems with ancient client or server implementations on internal networks. To address this problem, you can revert the changes with: Postfix SMTP client settings: lmtp_tls_ciphers = export smtp_tls_ciphers = export lmtp_tls_protocols = !SSLv2 smtp_tls_protocols = !SSLv2 lmtp_tls_mandatory_protocols = !SSLv2 smtp_tls_mandatory_protocols = !SSLv2 Postfix SMTP server settings: smtpd_tls_ciphers = export smtpd_tls_protocols = smtpd_tls_mandatory_protocols = !SSLv2 These settings, if put in, affect all Postfix SMTP client or server communication, which may be undesirable. To be more selective, use "-o name=value" parameter overrides on specific services in Execute the command "postfix reload" to make the changes effective. [Incompat 20150719] The default Diffie-Hellman non-export prime was updated from 1024 to 2048 bits, because SMTP clients are starting to reject TLS handshakes with primes smaller than 2048 bits. Historically, this prime size is not negotiable, and each site needs to determine which prime size works best for the majority of its clients. See FORWARD_SECRECY_README for some hints in the quick-start section.