Alias file include files
Other files can be included in the primary alias file. A line of the form
directs the MTA to read the file
file-spec. The file specification must be a complete file path specification and the file must have the same protections as the primary alias file; i.e., it must be world readable.
The contents of the included file are inserted into the alias file at its point of reference. The same effect can be achieved by replacing the reference to the included file with the file's actual contents. The format of include files is identical to that of the primary alias file itself. Indeed, include files may themselves include other files. Up to three levels of include file nesting are allowed.
If a compiled configuration is being used, then the configuration must be recompiled and reinstalled before changes to any included file (or the primary alias file itself) will take effect. Note that this is not the case for mailing list membership files described in Alias file mailing list aliases.