After 6 months of development release of the mail server , which includes accumulated fixes and new features. According to May's about a million mail servers, Exim holds 57.59% market share (up from 53.03% a year ago), Postfix is used on 34.70% (34.51%) of mail servers, Sendmail — 3.75% (4.05%), Microsoft Exchange — 0.42% (0.57%).
Changes in the new release may lead to a breach of backward compatibility. In particular, some transport types have stopped working with tainted data (data based on input from the sender) when determining delivery locations. For example, issues may arise when using the $local_part variable in the check_local_user setting when routing messages. Instead of $local_part, the new sanitized variable '$local_part_data' should be used. Additionally, in the headers_remove option operands, it is now allowed to use masks defined by the '*' symbol, which may lead to misconfigurations where headers ending with an asterisk were removed (instead of removing specific headers, removals will occur based on the mask).
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- Experimental built-in support for the SRS (Sender Rewriting Scheme) mechanism has been added, allowing the sender's address to be rewritten during forwarding without violating SPF checks () and ensuring that the sender's data is preserved for the server to direct messages in the event of a delivery failure. The essence of the method is that when establishing a connection, information about the identity with the original sender is transmitted; for example, when rewriting alice@example.org to alice@example.com, it will show 'SRS0=HHH=TT=example.org=alice@example.com'. SRS is relevant, for instance, when organizing mailing lists where the original message is forwarded to other recipients.
- When using OpenSSL, support for channel pinning has been added for (previously only supported for GnuTLS).
- The 'msg:defer' event has been added.
- Support for the client-side gsasl authenticator has been implemented, which has only been tested with the plaintext handler. The SCRAM-SHA-256 and SCRAM-SHA-256-PLUS methods can only operate via gsasl itself. .
- Support for the gsasl authenticator has been implemented on the server side for encrypted passwords, serving as an alternative to the previously available plaintext mode.
- Definitions in named lists can now be prefixed with 'hide' to suppress content output when executing the '-bP' command.
- Experimental support for internet sockets has been added to the Dovecot IMAP server authentication driver (previously, only unix-domain sockets were supported).
- The ACL expression 'queue_only' can now be specified as 'queue' and supports the 'first_pass_route' option, similar to the command line option '-odqs'.
- New variables $queue_size and $local_part_{pre,suf}fix_v have been added.
- The main configuration block now includes the 'sqlite_dbfile' option for use when defining the search string prefix. This change breaks backward compatibility—the old method of specifying the prefix no longer works when using untainted variables in lookup queries. The new method ('sqlite_dbfile') allows the file name to be held separately.
- Options for returning the full path and filtering file types during matching have been added to the dsearch lookup blocks.
- Options for specifying the server name separately from the search string have been added to the pgsql and mysql lookup blocks.
- For lookup blocks performing a single key selection, an option has been added to return a cleaned (de-tainted) version of the key when matches exist, instead of the searched data.
- For all successful list-match selections, the variables $domain_data and $localpart_data are set (previously, the matched list elements were inserted). Additionally, the elements used in the matching are now assigned to the variables $0, $1, etc.
- The expansion operator '${listquote {} {}}' has been added.
- An option has been added to the expansion operator ${readsocket {}{}{}} to ensure that results are cached.
- The dkim_verify_min_keysizes setting has been added to list the minimum acceptable sizes for public keys.
- The parameters 'bounce_message_file' and 'warn_message_file' are expanded before their first use.
- The 'spf_smtp_comment_template' option has been added to configure the value of the variable '$spf_smtp_comment'.
Source: opennet.ru
