Project mailfromd
mailfromd
8.17
— 
2023-07-07
* Multiple handler definitions Multiple "prog" declarations with the same handler name are now allowed. Such declarations are processed the same way multiple "begin" and "end" sections were processed in prior versions: when compiling the filter program, the code from all "prog" declarations having the same handler name is combined into one code block, in the same order the declarations appear in the source file(s). This allows MFL modules to define handler snippets. * New special handler: action The "action" special handler is executed before communicating the reply action (accept, reject, etc.) to the server. The handler takes four arguments: numeric identifier of the action that is about to be returned, SMTP response code, extended response code, and textual message passed along with the action. The last three arguments are meaningful only for reject and tempfail actions. Action handlers can be used for logging or accounting of the executed actions. * New variable: milter_state The milter_state variable is initialized with the numeric code of the current milter state. Using this variable a function can execute code depending on the handler it was called from. The new module "milter.mfl" defines numeric constants for milter states. The functions milter_state_name and milter_state_code can be used to convert this code to symbolic name and vice versa. * New functions The following new functions are provided to convert numeric identifiers of various MFL entities to strings and vice-versa: ** string milter_state_name (number code) Returns symbolic name of the milter state identified by its code. ** number milter_state_code (string name) Returns numeric code of the state identified by its name. ** string milter_action_name (number code) Returns symbolic name of the reply action identified by its code. ** number milter_action_name (string name) Returns numeric code of the action identified by its name. ** void dbbreak (number @var{dbn}) Stop sequential access to the database and deallocate all associated resources. Use this function if you need to break from the sequential access loop, e.g.: loop for number dbn dbfirst(dbname) do if some_condition dbbreak(dbn) break fi done while dbnext(dbn) * New module: cdb The "cdb" (control database) module provides functions for deciding what MFL action to take depending on the result of a look up in a DBM file. Keys in the database have the format "PREFIX:KEY", where PREFIX is one of: email match sender email ip match sender IP address domain match sender domain part subdomain search for a match among the domain part and its parent domains mx match MX of the sender domain part Values are (case-insensitive): OK continue executing the MFL code ACCEPT accept the mail REJECT reject the mail (550) TEMPFAIL return a temporary failure (451) GREYLIST greylist the mail or action specification in the form [code [xcode]] text where code is 3-digit SMTP response code, xcode is extended SMTP code, and text is explanatory reason text. Both code and xcode must begin with '4' or '5'. If code and xcode are missing, reject the mail with 550 5.1.0 and the given text. This module exports one function: func cdb_check(string prefix, string key) Depending on the value of the prefix argument it does the following: ip Look up the "ip:KEY" in the database. If found, take the action as described above. email Key is an email address. Obtain its canonical form by splitting it into local and domain parts, converting the latter to lower case, reassembling the parts back into an email address and prefixing it with the string "email:". Look up the resulting string in the database. Take action indicated by the value. domain Key is an email address. Extract its domain part, convert it to lower case and prefix it with "domain:". Look up resulting string in the database. If the look up succeeds, take action indicated by the value found. subdomain Same as above, but in case of failure, strip the shortest hostname prefix (everything up to the first dot, inclusively) from the domain and restart with the resulting value. Continue process until a match is found or the argument is reduced to empty string. mx Key is an email address. Extract its domain part. For each of its MX servers, look up the key "mx:SERVER" and, if found, take action indicated by the value found. The cdb_check function returns to caller only if the key was not found in the database, or the lookup returned "OK" (case-insensitive) or an empty string. Otherwise, if the lookup returns an action, this action will be performed and further execution of the filter code will stop. If the looked up value was "GREYLIST" while the function was called from the handler prior to "envrcpt" (i.e. "connect", "helo", or "envfrom"), the current handler will return and normal control flow will resume from the next handler (as if by "continue" action). Actual greylisting will be performed later, on entry to "envrcpt" handler. The following global variables control the functionality of the module: cdb_name Name of the control database file. Defaults to /etc/mail/mfctl.db cdb_greylist_interval Greylisting time. Defaults to 900 seconds. * mtasim: check expected textual replies The "\E" command accepts optional second argument. If supplied, it is treated as an extended regular expression. The subsequent command will then succeed if its return code matched the one supplied as the first argument, and its extended SMTP code and textual message match the supplied regular expression. * Bugfixes ** mtasim: correctly pass final body chunk to the milter ** Fix discrepancy between $N and $(N) Both terms now mean exactly the same: Nth variadic argument. ** fix type conversions of typed variadic arguments ** Milter library: eliminate trailing space from arguments passed to handlers ** Milter server: don't pass extra \0 when sending multiple strings ** Fix handling of reply actions without explicit message text In previous versions, the reject and tempfail actions would use the default reply code if called without explicit message text (3rd argument).
Mailfromd is a general-purpose mail filtering daemon for Sendmail, Postfix and MeTA1. It is able to filter both incoming and outgoing messages using criteria of arbitrary complexity, supplied by the administrator in the form of a script file. The daemon interfaces with the MTA using Milter or PMilter protocols.