10.1 Calloutd Configuration

Main configuration file /etc/mailfromd.conf is used (see Mailfromd Configuration). The configuration statements are basically the same as for mailfromd.

The address to listen on is defined in the server statement. Basically, it is the only statement the configuration file is required to have. The minimal configuration can look like:

program calloutd {
  server {
    listen inet://198.51.100.1:3535;
  }
}  

To instruct the mailfromd daemon to use this server, the following statement should be added to the /etc/mailfromd.conf file:

program mailfromd {
  callout-url inet://198.51.100.1:3535;
}  

The server statement differs a little from the similar statement for mailfromd. This and another calloutd-specific statements are described in detail in the subsections that follow. The rest of statements is shared with mailfromd. The following table lists all supported configuration statements along with cross-references to the correspondent descriptions:

10.1.1 calloutd General Setup

Calloutd Conf: source-ip IP

Sets source IP address for TCP connections.

Calloutd Conf: pidfile filename

Defines the name of the file to store PID value in.

Calloutd Conf: state-directory dir

Sets the name of the program state directory. See statedir.

10.1.2 The server statement

The server statement configures how calloutd will communicate with the client mailfromd server.

server {
  id name;
  listen url;
  backlog num;
  max-instances num;
  single-process bool;
  reuseaddr bool;
  default bool;
  callout url;
  acl { … }
}

Calloutd Conf: server

Define a server. Optional label may follow the server keyword. The label is ignored.

The substatements in the server block provide parameters for configuring this server.

server: id name

Assign an identifier to this server. This identifier is used as a suffix to syslog tag (see syslog tag) in messages related to this server. For example, if a server block had the following statement in it:

id main;

then all messages related to this server will be marked with tag ‘calloutd#main’.

The part before the ‘#’ is set using the tag statement in logging block (see Mailutils Configuration File in GNU Mailutils Manual).

server: listen url

Listen for connections on the given URL. See milter port specification, for a description of allowed url formats.

Example:

listen inet://10.10.10.1:3331;

server: backlog num

Configures the size of the queue of pending connections. Default value is 8.

server: max-instances number

Sets the maximum number of instances allowed for this server.

server: single-process bool

When set to ‘yes’, this server will run in single-process mode, i.e. it will not fork sub-processes to serve requests. This option is meant exclusively to assist in debugging calloutd. Don’t use it for anything else but for debugging!

server: reuseaddr bool

When set to ‘yes’, calloutd will attempt to reuse existing socket addresses. This is the default behavior.

server: acl statements

Defines access control list for this server. See Mailutils Configuration File in GNU Mailutils Manual, for a detailed discussion.

If the global ACL is defined as well, an incoming connection is checked against both lists: first the per-server ACL, then the global one. The connection will be permitted only if it passes both checks.

10.1.3 calloutd logging

Calloutd Conf: logger mech

Set default logger mechanism. Allowed values for mech are:

stderr

Log everything to the standard error.

syslog

Log to syslog.

syslog:async

Log to syslog using the asynchronous syslog implementation.

See Logging and Debugging, for a detailed discussion. See also Using non-blocking syslog, for information on how to set default syslog implementation at compile time.

Calloutd Conf: debug spec

Set mailfromd debug verbosity level. The spec must be a valid debugging level specification (see debugging level specification).

Calloutd Conf: transcript bool

If the boolean value bool is ‘true’, enables the transcript of call-out SMTP sessions.