Incoming Mail Filter

The Incoming Mail Filter facility allows you to control what messages are accepted by a mailbox. This facility in combination with use of the Aliases-tab allows the construction of powerful mail filtering and message routing. The IMF is set from the Mail-tab at the [Incoming Mail Filter] button.

Do not confuse this facility with the Filters-tab which controls folder filtering within the mailbox.
Care needs to be taken in the use of filters to make sure mail is not inadvertantly lost. Messages excluded by the IMF are permanantly deleted and cannot be recovered.

Filter Settings Tab
The tab consists of a two column table with each row of that table providing an individual customisable filter setting. Each filter setting is a combination of a Filter Criteria and a field value. Mailtraq performs case insensitive matches on the contents of field values, which may also contain the following wildcards:-

* An asterisk (ASCII 42) which represents any sequence of zero or more characters
? A question mark(ASCII 63) which represents any single character
% A percentage sign(ASCII 37) which represents any single number

Messages can be either included or excluded from being acted on by Mailtraq by placing suitable entries in the Filter Criteria table and setting a Match type accordingly.

Filter Criteria
Mailtraq provides an extensive list of standard Filter Criteria but any header name can also be used if required by overwriting the existing text in a criteria field. The headers of a message can be viewed in the console by selecting a message and choosing View from its context menu. The headers appear at the top of messages and are separated by a single blank line from message bodies.

Filter Criteria

The standard Filter Criteria available, which equate to the header fields found in most mail and news messages, are as follows:-

Sender
From
To
Cc
Bcc
Organisation
Newsgroups
Subject
Reply-To
Return-Path
Message-ID
Return-Receipt-To

Mailtraq also provides the following standard Filter Criteria which express other useful message properties:-

#size the size of a message in lines
#body the contents of the body text of a message
#minrcpts the minimum number of recipients of a message
#maxrcpts the maximum number of recipients of a message
#minsize the minimum size of a message
#maxsize the maximum size of a message
#priority the priority setting of a message ("high" / "low")

The header fields of a message can be viewed by selecting the message in the console and choosing View from its context menu. The header fields begin at the top of the message and are separated from the text of the message body by a single blank line.

Custom headers not found in the above list may also be entered as Filter Criteria by overwriting the existing text in that field. Note that the colon which appears after all header fields must not be entered into the Filter Criteria.
 

Filter Examples

A filter entry consists of two fields, an entry in the Filter Criteria and a corresponding field value, for example:-

Filter Criteria Field Value
Subject dollar

...traps any message in which the Subject: header includes the text 'dollar' anywhere in that header field. Mailtraq makes case insensitive matches against the field values in filters thus that entry would also match 'Dollar' and 'DoLLar'. The standard wildcards available in Mailtraq can also be used in the field value, for example:-

Filter Criteria Field Value
To *@example.com

...traps any message addressed in the To: header to any user at the example.com domain.

Custom headers may also be used in the Filter Criteria by overwriting the existing text. Some service providers, for example, use the non standard X-Apparently-To: header to record the message envelope forward address:-

Filter Criteria Field Value
X-Apparently-To fred

...traps any message in which that header holds an address containing the text 'fred'. That selection can be reversed by negating the Filter Criteria with a tilde "~" character (ASCII 126). For example, to trap all messages with 'example.com' in the To: header which do not contain the text 'fred' in the X-Apparently-To: header:-

Filter Criteria Field Value
To *@example.com
~X-Apparently-To fred

Note that Mailtraq applies implicit wildcards either side of field values (that is, a value of 'fred' matches both 'user@fred.example.com' and 'fred@example.com') but wildcards are otherwise required (that is, a value of 'make money' fails to trap 'make big money' but a value of 'make*money' traps both 'make money' and 'make big money').

Mailtraq filters can also be configured to act only if multiple conditions are met. For example, if messages are to be excluded only if they contain both an address in the Sender: header and a subject which includes the text "Foobar":-

Match

The Match type modifies how a match is obtained:-

All - the message is included only if all entries match
Any - the message is included if any entries match
None - the message is included only if no entries match
Not All - the message is excluded only if all entries match

Configuration Tip

Note carefully the context in which filters are used. In some cases filter matches include messages, in other cases filter matches exclude messages.

 For example:

Set Filter Criteria - To: Field Value - user@domain.com 
Set Filter Criteria - From: Field Value - user@domain.com

Match - Any

will only allow messages into the mailbox that are either To or From user@domain.com 
All other messages will be discarded and cannot be recovered.

It is useful to recall that you can drag copies of messages from another mailbox into the one that you are setting the Filter on. This makes it easy to test if your filter rules are working as expected.