This is the Postfix 3.9 experimental release. The stable Postfix release is called postfix-3.8.x where 3=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-3.9-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 3.7 or earlier, please read RELEASE_NOTES-3.8 before proceeding. Dual license ------------ As of Postfix 3.2.5 this software is distributed with a dual license: in addition to the historical IBM Public License (IPL) 1.0, it is now also distributed with the more recent Eclipse Public License (EPL) 2.0. Recipients can choose to take the software under the license of their choice. Those who are more comfortable with the IPL can continue with that license. Incompatible changes with snapshot 20231221 =========================================== Postfix 3.9 by default disconnects a client that sends a 'bare newline' ending in SMTP. This prevents an SMTP smuggling attack that targets recipients at a Postfix server. For background, see https://www.postfix.org/smtp-smuggling.html For compatibility with non-standard clients, Postfix 3.9 by default excludes clients in mynetworks from this countermeasure. The Postfix 3.9 default settings are: # Disconnect remote SMTP clients that send bare newlines, but # allow local clients with non-standard SMTP implementations # such as netcat, fax machines, or load balancer health checks. # smtpd_forbid_bare_newline = yes smtpd_forbid_bare_newline_exclusions = $mynetworks This feature is back-ported to all supported stable releases, with the difference that "smtpd_forbid_bare_newline = no" by default. Incompatible changes with snapshot 20230903 =========================================== The MySQL client no longer supports MySQL versions < 4.0. MySQL version 4.0 was released in 2003. Major changes with snapshot 20230901 ==================================== New parameter force_mime_input_conversion (default: no) to convert body content that claims to be 8-bit into quoted-printable, before header_checks, body_checks, Milters, and before after-queue content filters. This feature does not affect messages that are sent into smtpd_proxy_filter. The typical use case is an MTA that applies this conversion before signing outbound messages, so that the signatures will remain valid when a message is later handled by an MTA that does not announce 8BITMIME support, or when a message line exceeds the SMTP length limit. Major changes with snapshot 20230807 ==================================== Optional Postfix TLS support to request an RFC7250 raw public key instead of an X.509 public-key certificate. The configuration settings for raw key public support will be ignored when there is no raw public key support in the local TLS implementation (i.e. Postfix with OpenSSL versions before 3.2). - With "smtpd_tls_enable_rpk = yes", the Postfix SMTP server will request that a remote SMTP client sends an RFC7250 raw public key instead of an X.509 certificate when asking for or requiring TLS client authentication. The Postfix SMTP server will still accept a client public-key certificate instead of a public key. - With "smtp_tls_enable_rpk = yes" (or "enable_rpk = yes" in an smtp policy table) at the security levels "may", "encrypt" or "fingerprint", the Postfix SMTP client will request that a remote SMTP server sends an RFC7250 raw public key instead of an X.509 certificate. The Postfix SMTP client will still accept a server public key certificate instead of a public key. - At the "secure" and "verify" security level, the Postfix SMTP client will ignore smtp_tls_enable_rpk or enable_rpk settings, because these levels require a server certificate. - At the "dane" and "dane-only" security levels, the Postfix SMTP client will ignore smtp_tls_enable_rpk or enable_rpk settings, and will request that a remote SMTP server sends an RFC7250 raw public key instead of an X.509 certificate when all valid TLSA records specify only server public keys (no certificates). The Postfix SMTP client will still accept a server public key certificate. - The Postfix SMTP client and server always send a raw public key instead of a certificate, if solicited by the remote SMTP peer and the local TLS implementation supports raw public keys. - If a remote SMTP client sends a server name indication with an SNI TLS extension, and tls_server_sni_maps is configured, the Postfix SMTP server will extract a raw public key from the indicated certificate. Caution: enabling Postfix raw key support will break authentication based on certificate fingerprints in check_ccert_access or smtp_tls_policy_maps, when a remote peer's TLS implementation starts to send a raw public key instead of a certificate. The solution is to always use public key fingerprint patterns; these will match not only a "raw" public key, but also the public key in a certificate. To detect such problems before they happen, the Postfix SMTP server will log a warning when it requests an RFC7250 raw public key instead of an X.509 certificate, the remote peer sends a certificate instead of a public key, and check_ccert_access has a matching fingerprint for the certificate but not for the public key in that certificate. There is no corresponding warning from the Postfix SMTP client. For instructions to generate public-key fingerprints, see the postconf(5) man pages for smtp_tls_enable_rpk and smtpd_tls_enable_rpk. Incompatible changes with snapshot 20230603 =========================================== Security: the Postfix SMTP server by default disconnects remote SMTP clients that violate RFC 2920 (or 5321) command pipelining constraints. The server replies with "554 5.5.0 Error: SMTP protocol synchronization" and logs the unexpected remote SMTP client input. Specify "smtpd_reject_unauth_pipelining = no" to disable. Major changes with snapshot 20230522 ==================================== Preliminary support for OpenSSL configuration files, primarily OpenSSL 1.1.1b and later. This introduces two new parameters "tls_config_file" and "tls_config_name", which can be used to limit collateral damage from OS distributions that crank up security to 11, increasing the number of plaintext email deliveries. Details are in the postconf(5) manpage under "tls_config_file" and "tls_config_name". Incompatible changes with snapshot 20230419 =========================================== The MySQL client default characterset is now configurable with the "charset" configuration file attribute. The default is "utf8mb4", consistent with the MySQL 8.0 built-in default, but different from earlier MySQL versions where the built-in default was "latin1".