Extensions can have a variable to switch them on or off. Unlike explicit otherwise stated, “0” (zero) is OFF and “1” (one) is ON. Invalid values will be taken as false (=OFF).
The documentation describes the recommended way how to install and configure a module with and for eQmail in the first place. Some common solutions for *qmail differs and will be mentioned in an alternative section (perhaps). This will happen especially if an exclusive feature of eQmail is usually not available on derivatives.
Placeholders are reserved terms which will be replaced during the build. These are the placeholders currently used:
Placeholders doesn't have to be used as variables!
*qmail follows a variant of the so called “slashpackage” convention. So by default
/var/qmail  is the home directory of qmail-1.03. The term home directory stands for the location were *qmail was (or will be) installed. Usual synonyms are “install dir”, “QMAILDIR”, “homedir”, “Home” or similar, even combinations of it and maybe with mixed upper/lower case letters.
Originally qmail was installed in
/var/qmail  by default. This is called the qmail home directory, so “QMAILHOME” points to the qmail home directory always. As openQmail and qmail derivatives can be installed in other locations too, “QMAILHOME” have to be read as the chosen replacement of the home directory.
Environment variables can be set in the “run” file of daemontools, the cdb file of tcpserver or in the config file of xinetd.