Optional or fixed with Postfix 3.8.1, 3.7.6, 3.6.10, 3.5.20:
Optional: harden a Postfix SMTP server against remote SMTP clients that violate RFC 2920 (or 5321) command pipelining constraints. With "smtpd_forbid_unauth_pipelining = yes", the server disconnects a client immediately, after responding with "554 5.5.0 Error: SMTP protocol synchronization" and after logging "improper command pipelining" with the unexpected remote SMTP client input. This feature is disabled by default in Postfix 3.5-3.8 to avoid breaking home-grown utilities, but it is enabled by default in Postfix 3.9. A similar feature is enabled by default in the Exim SMTP server.
Optional: some OS distributions crank up TLS security to 11, and in doing so increase the number of plaintext email deliveries. This introduces basic OpenSSL configuration file support that may be used to override OS-level settings. Details are in the postconf(5) manpage under tls_config_file and tls_config_name.
Bugfix (defect introduced: Postfix 1.0): the command "postconf .. name=v1 .. name=v2 .." (multiple instances of the same parameter name) created multiple main.cf name=value entries with the same parameter name. It now logs a warning and skips the earlier name(s) and value(s). Found during code maintenance.
Bugfix (defect introduced: Postfix 3.3): the command "postconf -M name1/type1='name2 type2 ...'" died with a segmentation violation when the request matched multiple master.cf entries. The master.cf file was not damaged. Problem reported by SATOH Fumiyasu.
Bugfix (defect introduced: Postfix 2.11): the command "postconf -M name1/type1='name2 type2 ...'" could add a service definition to master.cf that conflicted with an already existing service definition. It now replaces all existing service definitions that match the service pattern 'name1/type1' or the service name and type in 'name2 type2 ...' with a single service definition 'name2 type2 ...'. Problem reported by SATOH Fumiyasu.
Fixed with Postfix 3.8.1:
Bugfix (defect introduced: Postfix 3.8) the posttls-finger command could access uninitialized memory when reconnecting. This also fixes a malformed warning message when a destination contains ":service" information. Reported by Thomas Korbar.
Bugfix (defect introduced: Postfix 3.2): the MySQL client could return "not found" instead of "error" (for example, resulting in a 5XX SMTP status instead of 4XX) during the time that all MySQL server connections were turned down after error. Found during code maintenance. File: global/dict_mysql.c. This was already fixed in Postfix 3.4-3.7.
Optional or fixed with Postfix 3.8.1, 3.7.6, 3.6.10, 3.5.20:
Fixed with Postfix 3.8.1: