Patches for Proofpoint to patch sendmail so that libmilter can be built as a dynamic shared object (libmilter.so).

Update: This was sent to Proofpoint on 8 December 2024

Many downstream users (Linux distributions, as well as FreeBSD and others) patch sendmail (or libmilter, if they package this separately) to build a shared object of libmilter.

This is an attempt to create a patch to send to upstream (Proofpoint) in the hope that they will implement this feature upstream.

The steps taken in this project to create a shared object are:

1. Copy the directory ${SRC}/libmilter to ${SRC}/libsharedmilter
2. Create ${SRC}/devtools/M4/UNIX/sharedlibrary.m4
3. Adapt ${SRC}/libsharedmilter/Makefile.m4 to build a shared object
4. Update various README files

The reason for building a shared object in a new directory, rather than the build process to the current libmilter feature, is that not al OS's that support sendmail use shared objects (e.g. AIX). Hence, we leave it to the builder of sendmail / libmilter to decide which version needs to be built.