sendmail filter configurations

Use these guidelines to specify the filters you want while configuring sendmail.

Specify filters using the key letter X (for eXternal). In the following example, three filters are specified:

    Xfilter1, S=local:/var/run/f1.sock, F=R
    Xfilter2, S=inet6:999@localhost, F=T, T=C:10m;S:1s;R:1s;E:5m
    Xfilter3, S=inet:3333@localhost

You can specify filters in your .mc file using the following syntax:

    INPUT_MAIL_FILTER(`filter1', `S=local:/var/run/f1.sock, F=R')
    INPUT_MAIL_FILTER(`filter2', `S=inet6:999@localhost, F=T, T=C:10m;S:1s;R:1s;E:5m')
    INPUT_MAIL_FILTER(`filter3', `S=inet:3333@localhost')

where filter(number) is the name of your filter. The first line of the syntax specifies that the filter attach to a socket in the UNIX domain in the /var/run directory. The second line specifies that the filter use an IPv6 socket on port 999 of the local host. The third line specifies that the filter use an IPv4 socket on port 3333 of the local host.

The F= denotes which of the following flags applies:

Item	Description
R	Rejects the connection if the filter is unavailable.
T	Fails the connection temporarily if the filter is unavailable.

If neither flag is specified, the message is passed through sendmail as if the filter were not present.

By specifying a value for T=, you can use the filters to override the default timeouts used by sendmail. The T= equate uses the following fields:

Item	Description
C	Timeout for connecting to a filter (if 0, use the system timeout).
S	Timeout for sending information from the MTA to a filter.
R	Timeout for reading replies from the filter.
E	Overall timeout between sending end-of-message notices to the filter and waiting for the final acknowledgement.

As indicated in the preceding example, the separators between each timeout is a semicolon (;), and the separator between each equate is a comma (,).

The default values for timeouts are as follows:

T=C:0m;S:10s;R:10s;E:5m

where s is seconds and m is minutes.

The InputMailFilters option determines which filters are used and in what sequence.

Note: If the InputMailFilters option is not specified, no filters are used.

The InputMailFilters option is set automatically according to the order of the INPUT_MAIL_FILTER commands in your .mc file. You can reset this value by setting a value for confINPUT_MAIL_FILTERS in your .mc file. For example, if the InputMailFilters option is set as:

InputMailFilters=filter1, filter2, filter3

the three filters will be called in the same order they were specified.

By using MAIL_FILTER() instead of INPUT_MAIL_FILTER() in your .mc file, you can define a filter without adding it to the input filter list.