Sieve Email Filtering: Include Extension

Sieve implementations that implement the "include", "return", and "global" commands described below have an identifier of "include" for use with the capability mechanism. If any of the "include", "return", or "global" commands are used in a script, the "include" capability MUST be listed in the "require" statement in that script. Sieve implementations must track the use of actions in included scripts so that implicit "keep" behavior can be properly determined based on whether any actions have executed in any script. Sieve implementations are allowed to limit the total number of nested included scripts, but MUST provide for a total of at least three levels of nested scripts including the top-level script. An error MUST be generated either when the script is uploaded to the Sieve repository, or when the script is executed, if any nesting limit is exceeded. If such an error is detected whilst processing a Sieve script, an implicit "keep" action MUST be executed to prevent loss of any messages. Sieve implementations MUST ensure that recursive includes are not possible. For example, if script "A" includes script "B", and script "B" includes script "A" an error MUST be generated either when the script is uploaded to the Sieve repository, or when the script is executed. If such an error is detected whilst processing a Sieve script, an implicit "keep" action MUST be executed to prevent loss of any messages. Sieve implementations MUST handle missing scripts being referenced via an includes in an existing script. An error MUST be generated when a missing included script is discovered during execution. If such an error is detected an implicit "keep" action MUST be executed to prevent loss of any messages. If the Sieve "variables" extension is present, an issue arises with the "scope" of variables defined in scripts that may include each other. For example, if a script defines the variable "${status}" with one particular meaning or usage, and another defines "${status}" with a different meaning, then if one script includes the other there is an issue as to which "${status}" is being referenced. To solve this problem, Sieve implementations MUST follow the scoping rules defined in and support the "global" command defined there.

LOCATION = ":personal" / ":global" ONCE = ":once" ]]> The "include" command takes an optional "location" parameter, an optional ":once" parameter, and a single string argument representing the name of the script to include for processing at that point. It is RECOMMENDED that implementations restrict script names according to Section 1.7. Implementations MUST NOT allow variables to be expanded into the names of Sieve scripts; in other words, the value MUST be a constant string as defined in by VARIABLES Section 3. The "location" parameter MUST default to ":personal" if not specified. The "location" has the following meanings: Indicates that the named script is stored in the user's own personal (private) Sieve repository. Indicates that the named script is stored in a site-wide Sieve repository, accessible to all users of the Sieve system. The ":once" parameter tells the interpreter only to include the named script if it has not already been included at any other point during script execution. If the script has already been included, processing continues immediately following the include command. Implementations MUST NOT generate an error if an "include :once" command names a script whose inclusion would be recursive; in this case, the script MUST be considered previously included and therefore "include :once" will not include it again. Note: It is RECOMMENDED that script authors / generators use this parameter only when including a script that performs general duties such as declaring global variables and making sanity checks of the environment. The included script MUST be a valid Sieve script, including having necessary "require" statements for all optional capabilities used by the script. The scope of a "require" statement in an included script is for the immediate script only, not the including script. For example, if script "A" includes script "B", and script "B" uses the "fileinto" extension, script "B" must have a "require" statement for "fileinto", irrespective of whether script "A" has one. In addition, if script "A" does not have a "require" statement for "fileinto", "fileinto" cannot be used anywhere in script "A", even after inclusion of script "B". A "stop" command in an included script MUST stop all script processing, including the processing of the scripts that include the immediate one. The "return" command (described below) stops processing of the immediate script only, and allows the scripts that include it to continue. Examples: The user has four scripts stored in their personal repository: "default" This is the default active script that includes several others. Personal script "always_allow" This script special cases some correspondent email addresses and makes sure any message containing those addresses are always kept. Personal script "spam_tests" This script does some user-specific spam tests to catch spam messages not caught by the site-wide spam tests. Personal script "mailing_lists" This script looks for messages from different mailing lists and files each into a mailbox specific to the mailing list. There is one script stored in the global repository: Site script "spam_tests" This script does some site-wide spam tests which any user at the site can include in their own scripts at a suitable point. The script content is kept up to date by the site administrator. The "include" command may appear anywhere in the script where a control structure is legal. Example:

The "return" command stops processing of the immediately included script only and returns processing control to the script which includes it. If used in the main script (i.e. not in an included script), it has the same effect as the "stop" command, including the appropriate "keep" action if no other actions have been executed up to that point.

In order to avoid problems of variables in an included script "overwriting" those from the script that includes it, this specification requires that all variables defined in a script MUST be kept "private" to the immediate script by default - i.e. they are not "visible" to other scripts. This ensures that two script authors cannot inadvertently cause problems by choosing the same name for a variable. However, sometimes there is a need to make a variable defined in one script available to others. This specification defines the new command "global" to declare that a variable is shared among scripts. Effectively, two namespaces are defined: one local to the immediate script, and another shared among all scripts. Implementations MUST allow a non-global variable to have the same name as a global variable but have no interaction between them.

]]> The "global" command contains a string list argument that defines one or more names of variables to be stored in the global variable space. If a "global" command is given the name of a variable that has been defined in the immediate script, any value stored in the global space is overwritten with the value of the variable in the script. If a "global" command lists a variable that has not been defined in the global namespace, the name of the variable is nonetheless marked as global, and any subsequent "set" command will set the value of the variable in global scope. Interpretation of a string containing a variable marked as global, but without any value set, SHALL behave as any other access to an unknown variable, as specified in Section 3 of (that is, the unknown variable reference evaltuates to an empty string). Example:

In addition to the "global" command, this document defines the variables namespace "global", per , Section 3. Example: Variables declared global and variables accessed via the global namespace MUST be one and the same. In the following example script, we see the variable "i_am_on_vacation" used in a "global" command, and again with the "global." namespace. Consider these as two syntaxes with identical meaning. Example: