1.2.6rc1 and later
The <IfModule test>...</IfModule> section is used to mark directives that are conditional. The directives within an IfModule section are only processed if the test is true. If the test is false, everything between the start and end markers is ignored.
The test in the <IfModule> section directive can be one of two forms: "module name" or "!module name"
In the former case, the directives between the start and end markers are only processed if the module named module name is compiled in to ProFTPD. The second format reverses the test, and only processes the directives if module name is not compiled in.
The module name argument is a module name as given as the file name of the module, at the time it was compiled. For example, mod_sql.c.
<IfModule> sections are nest-able, which can be used to implement simple multiple-module tests.