5 {pmg} ships with a highly configurable mail filter. It’s an easy but
6 powerful way to define filter rules by user, domains, time frame,
7 content type and resulting action.
9 image::images/screenshot/pmg-gui-mail-filter-rules.png[]
11 Every rule has 5 categories ('FROM', 'TO', 'WHEN', 'WHAT' and
12 'ACTION'), and each category may contain several objects to match
17 Who is the sender or receiver of the e-mail? Those objects can be used
18 for the 'TO' and/or 'FROM' category.
21 Example: EMail-object - Who is the sender or receiver of the e-mail?
26 What is in the e-mail?
29 Example: Does the e-mail contain spam?
34 When is the e-mail received by {pmg}?
37 Example: Office Hours - Mail is received between 8:00 and 16:00.
42 Defines the final actions.
45 Example: Mark e-mail with “SPAM:” in the subject.
48 Rules are ordered by priority, so rules with higher priority are
49 executed first. It is also possible to set a processing direction:
51 'In':: Rule applies for all incoming e-mails
53 'Out':: Rule applies for all outgoing e-mails
55 'In & Out':: Rule applies for both directions
57 And you can also disable a rule completely, which is mostly useful for
58 testing and debugging. The 'Factory Defaults' button alows you to
59 reset the filter rules.
62 [[pmg_mailfilter_action]]
66 image::images/screenshot/pmg-gui-mail-filter-actions.png[]
68 Please note that some actions stops further rule precessing. We call
74 Accept mail for Delivery. This is a 'final' action.
80 Block mail. This is a 'final' action.
86 Move to quarantine (virus mails are moved to the “virus quarantine”,
87 other mails are moved to “spam quarantine”). This is also a 'final' action.
93 Send notifications. Please note that object configuration can use
94 xref:rule_system_macros[macros], so it is easy to include additional
95 information. For example, the default 'Notify Admin' object sends the
96 following information:
98 .Sample notification action body:
100 Proxmox Notification:
102 Receiver: __RECEIVERS__
105 Matching Rule: __RULE__
113 Notification can also include a copy of the original mail.
116 Blind Carbon Copy (BCC)
117 ~~~~~~~~~~~~~~~~~~~~~~~
119 The BCC object simply sends a copy to another target. It is possible to
120 send the original unmodified mail, or the processed result. Please
121 note that this can be quite different, i.e. when a previous rule
128 This object is able to add or modify mail header attributes. As notice above, you can use xref:rule_system_macros[macros], making this a very powerful object. For example, the 'Modify Spam Level' actions adds detailed infomation about detected Spam characteristics to the ` X-SPAM-LEVEL` header.
130 .'Modify Spam Level' Header Attribute
136 Another prominent example is the 'Modify Spam Subject' action. This
137 simply adds the 'SPAM:' prefix to the original mail subject:
139 .'Modify Spam Subject' Header Attribute
142 Value: SPAM: __SUBJECT__
149 Remove attachments can either remove all attachments, or only those
150 matched by the rules 'What' - object. You can also specify the
151 replacement text if you want.
160 [[pmg_mailfilter_who]]
164 image::images/screenshot/pmg-gui-mail-filter-who-objects.png[]
166 This type of objects can be used for the 'TO' and/or 'FROM' category,
167 and macth the sender or receiver of the e-mail. A single object can
168 combine multiple items, and the following item types are available:
172 Allows you to match a single mail address.
176 Only match the domain part of the mail address.
180 This one uses a regular expression to match the whole mail address.
182 IP Address or Network::
184 This can be used to match the senders IP address.
188 Test if the mail address belong to a specific LDAP user or group.
190 We have two important 'Who' - objects called 'Blacklist' and
191 'Whitelist'. Those are used in the default ruleset to globally block
192 or allow specific senders.
195 [[pmg_mailfilter_what]]
199 image::images/screenshot/pmg-gui-mail-filter-what-objects.png[]
201 'What' - objects are used to classify the mail content. A single
202 object can combine multiple items, and the following item types are
207 Matches if configured value if greater than the detected spam level.
211 Matches on infected mails.
215 Match specified mail header fields (eg. `Subject:`, `From:`, ...)
217 Content Type Filter::
219 Can be used to match specific content types.
223 Uses regular expressions to match attachment filenames.
227 Can be used to match specific content types inside archives.
230 [[pmg_mailfilter_when]]
234 image::images/screenshot/pmg-gui-mail-filter-when-objects.png[]
236 'When' - objects are use to activate rules at specific daytimes. You
237 can compose them of one or more time-frame items.
239 The default ruleset defines 'Office Hours', but this is not used by
243 [[pmg_mailfilter_regex]]
244 Using regular expressions
245 -------------------------
247 A regular expression is a string of characters which tells us which
248 string you are looking for. The following is a short introduction in
249 the syntax of regular expressions used by some objects. If you are
250 familiar with Perl, you already know the syntax.
252 Simple regular expressions
253 ~~~~~~~~~~~~~~~~~~~~~~~~~~
255 In its simplest form, a regular expression is just a word or phrase to
256 search for. `Mail` would match the string "Mail". The search is case
257 sensitive so "MAIL", "Mail", "mail" would not be matched.
262 Some characters have a special meaning. These characters are called
263 metacharacters. The Period (`.`) is a commonly used metacharacter. It
264 matches exactly one character, regardless of what the character is.
265 `e.mail` would match either "e-mail" or "e-mail" or "e2mail" but not
268 The question mark (`?`) indicates that the character immediately
269 preceding it either zero or one time. `e?mail` would match
270 either "email" or "mail" but not "e-mail".
272 Another metacharacter is the star (`*`). This indicates that the
273 character immediately to its left may repeated any number of times,
274 including zero. `e*mail` would match either "email" or "mail" or
277 The plus (`+`) metacharacter does the same as the star (*) excluding
278 zero. So `e+mail` does not match "mail".
280 Metacharacters may be combined. A common combination includes the
281 period and star metacharacters (`.*`), with the star immediately following
282 the period. This is used to match an arbitrary string of any length,
283 including the null string. For example: `.*company.*` matches
284 "company@domain.com" or "company@domain.co.uk" or
285 "department.company@domain.com".
287 The book xref:Friedl97[] provides a more comprehensive introduction.