So far, we have talked only about how to use Exim, assuming that it is already installed on your system. We have not yet covered how to get it there. There are three possibilities:
Some operating systems (for example, Debian GNU/Linux) are now distributed with Exim already installed. If yours is one of these, you do not need to do anything, unless you want to use some of the optional code that is not included in your binary or you want to upgrade to a later release. If you do, you will have to fetch the source and compile it yourself.
Some operating systems (for example, FreeBSD) have a standardized “ports” mechanism, with a simple command that fetches the Exim source, compiles it with a particular set of options, and installs it for you. Again, if the options are suitable, you need do no more; if not, you must recompile, but in this scenario, the source is already available on your host. However, if you want to upgrade to a later release, you will have to fetch a new source.
If neither of these apply to you, you will have to fetch a copy of the source yourself, and then compile and install it.
There is no general repository of binary distributions. One reason for this is there are a number of choices to be made when compiling Exim; for example, whether to include support for database lookups, and if so, for which database. Thus a single binary (even for one operating system) would suit only a few people.
This chapter describes the process of ...