Sun Java System Messaging Server 6.3 Administration Reference

The MTA Configuration Files

This section explains the structure and layout of the MTA configuration files. Some configuration modifications are performed by using the command-line interface, as described in Chapter 2, Message Transfer Agent Command-line Utilities. Modifications not possible through the command line are performed by editing the configuration files. We recommend that only experienced administrators edit and modify the configuration files.

All configuration files are ASCII text files that are created or changed with any text editor. Permissions for the configuration file should be set to world-readable. Failure to make configuration files world-readable may cause unexpected MTA failures. A physical line in most files is limited to 252 characters and you can split a logical line into multiple physical lines using the backslash (\) continuation character.

Note –

The MTA processes read most of their configuration from the file .../config.dat. This file is the compiled form of the configuration build from the various text configuration files.

Some configuration files are not compiled into this compiled configuration file. In particular, dispatcher.cnf, job_controller.cnf, and the channel option files, for instance tcp_local_option, are not in the compiled configuration, so it is not necessary to compile the configuration to activate changes to these files. However, they are only read by processes when they start. Thus, to activate a change to the job controller's configuration, it is necessary to restart the job controller.

The compiled configuration itself is in two parts. Some, like the rewrite rules and channel definitions, can not be reloaded by running processes. To activate a change to part of the configuration that can not be reloaded, it is necessary to recompile the configuration and then to restart the processes that are affected. For instance, changes to the rewrite rules affect any process that enqueues messages. Thus a change to rewrite rules would require the configuration to be recompiled, and the dispatcher and the job controller to be restarted (thus causing a new generation of tcp_smtp_servers and delivery channel programs to be started.

Some of the configuration, for instance the mappings, aliases, and the general, reverse, and forward lookup tables are reloadable. Changes to these files can be activated by recompiling the configuration and issuing the imsimta reload command. The imsimta reload command informs all the running processes that they should reload the reloadable part of the compiled configuration.

Table 4–1 lists the MTA configuration files with a short description.

Table 4–1 MTA Configuration files


File	Description
Alias File (mandatory)	Implements aliases not present in the directory. `msg-svr-base/config/aliases`
SMTP Channel Option Files	Sets channel specific options. `msg-svr-base/config/channel_option`
Conversion File	Used by conversion channel to control message body part conversions. `msg-svr-base/config/conversions`
Dispatcher Configuration File (mandatory)	Specifies configuration file options for the service dispatcher. `msg-svr-base/config/dispatcher.cnf`
`forward.txt` (optional)	A text look up file, equivalent in function to the forward database. It provides an alternative mechanism to the LDAP directory for converting to addresses in messages flowing through the system. Setting bit 2 (value 4) of the MTA option `USE_TEXT_DATABASES` enables the use of this file instead of the reverse database. The file is converted into a hash table that is loaded into memory as part of the reloadable configuration. Only used if the MTA option `USE_FORWARD_DATABASE` is set
`general.txt` (optional)	(optional) A general text look up file. This file has the same function as the general database. Setting bit 0 (value 1) of the MTA option `USE_TEXT_DATABASES` enables use of this file instead of the general database. The file is converted into a hash table that is loaded into memory as part of the reloadable configuration.
Job Controller Configuration File (mandatory)	Defines Job Controller options `msg-svr-base/config/job_controller.cnf`
MTA Configuration File (mandatory)	Defines address rewriting and routing as well as channel definition. `msg-svr-base/config/imta.cnf`
Mapping File (mandatory)	Repository of mapping tables. `msg-svr-base/config/mappings`
Option File	Defines global MTA options. `msg-svr-base/config/option.dat`
`reverse.txt` (optional)	A text look up file, equivalent in function to the reverse database. It provides an alternative mechanism to the LDAP directory for converting from: addresses in messages flowing through the system. Setting bit 1 (value 2) of the MTA option `USE_TEXT_DATABASES` enables the use of this file instead of the reverse database. The file is converted into a hash table that is loaded into memory as part of the reloadable configuration. Only used if the MTA option `USE_REVERSE_DATABASE` is set.
Tailor File (mandatory)	Specifies locations. `msg-svr-base/config/imta_tailor`

Table 4–2 lists the MTA database files with a short description.

Table 4–2 MTA Database Files


File	Description
Reverse Database	Changes from: address in outgoing mail. This provides an alternative mechanism to using the directory, and is for specialized purposes only. An alternative to the reverse database is the reverse lookup table described in Table 4–1.
Forward Database	Changes to: address in outgoing mail. This provides an alternative mechanism to using the directory, and is for specialized purposes only. An alternative to the forward database is the forward lookup table described in Table 4–1.
General Database	Used with domain rewriting rules or in mapping rules, for site-specific purposes. `msg-svr-base/data/db/generaldb.db`. An alternative to the general database is the general lookup table described in Table 4–1.