The reverse and noreverse channel keywords, and the MTA options USE_REVERSE_DATABASE and REVERSE_ENVELOPE are used to control the specifics of when and how address reversal is applied. By default, the address reversal operation applies to all addresses, not just to backward pointing addresses.
Address reversal can be enabled or disabled by setting the value of the REVERSE_ENVELOPE system option (Default: 1-on, 0-off).
noreverse on the destination channel specifies that address reversal is not applied to addresses in messages. reverse specifies that address reversal is applied. See 12.6.9 Enabling Channel-Specific Use of the Reverse Database for details.
USE_REVERSE_DATABASE controls whether the MTA uses the address reversal text database and REVERSE mapping as a source of substitution addresses. A value of 0 means address reversal is not used with any channel. A value of 5 (default) specifies that address reversal is applied to all addresses—not just to backward pointing addresses— after they have been rewritten by the MTA address rewriting process. A value of 13 specifies that address reversal is applied to addresses with the reverse channel keyword—not just to backward pointing addresses— after they have been rewritten by the MTA address rewriting process. Further granularity of address reversal operation can be specified by setting the bit values of the USE_REVERSE_DATABASE option. See Option File Format and Available Options in Sun Java System Messaging Server 6.3 Administration Reference for details.
The REVERSE_ENVELOPE option controls whether or not address reversal is applied to envelope From addresses as well as message header addresses.
See the detailed descriptions of these options and keywords in the Sun Java System Messaging Server Administration Reference for additional information on their effects.
An example of a general REVERSE Mapping is as follows: suppose that the internal addresses at siroe.com are of the form email@example.com. However, the user name space is such that firstname.lastname@example.org and email@example.com specify the same person for all hosts at siroe.com. The following REVERSE mapping may be used in conjunction with the address-reversal text database:
REVERSE *@*.siroe.com $firstname.lastname@example.org$Y$D
In this example, addresses of the form email@example.com would be changed to firstname.lastname@example.org. The $D metacharacter causes the address-reversal database to be consulted. The address-reversal text database should contain entries of the form:
REVERSE email@example.com $D$YRebecca.Woods@siroe.com
This entry tells the MTA that for any mail with source channel of tcp_* going out the destination channel of tcp_local to change addresses of the form firstname.lastname@example.org to Rebecca.Woods@siroe.com
To enable channel-specific reverse mapping, you must set USE_REVERSE_DATABASE option in option.dat to 13. (Default=5.)