7.5 Server Configuration

A single mailfromd daemon can run several servers. These are configured in the following statement:

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

Mailfromd Conf: server type

Define a server. The type is either ‘milter’ or ‘callout’. See SMTP Timeouts, for a description of various types of servers.

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 ‘mailfromd#main’.

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

This identifier can be inspected from the MFL code using the milter_server_id variable (see milter_server_id).

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;

The MFL code can access its address using the milter_server_address and milter_server_family variables.

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 mailfromd. Don’t use it for anything else but for debugging!

server: reuseaddr bool

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

If the server type is ‘callout’, the following statement is also allowed:

server: option list

Configures server options. As of version 9.0 only one option is defined:

default

Mark this server as the default one. This means it will be used by every milter server that doesn’t define the callout-url statement.

server: default bool

When set to ‘yes’, this server is marked as a default callout server for all milter servers declared in the configuration. This is equivalent to option default.

if the server type is ‘milter’, you can use the following statement to query a remote callout server:

server: callout url

Use a callout server at url (see milter port specification).

You can also set a global callout server, which will be used by all milter servers that do not set the callout statement:

Mailfromd Conf: callout-url url

Set global callout server. See milter port specification, for allowed url formats.