{stdenv, fetchurl, tlsSupport ? false, openssl ? null}:

assert tlsSupport -> openssl != null;

stdenv.mkDerivation {
  name = "ssmtp-2.61-12";
  src = fetchurl {
    url = http://ftp.debian.org/debian/pool/main/s/ssmtp/ssmtp_2.61.orig.tar.gz;
    sha256 = "2151ad18cb73f9a254f796dde2b48be7318b45410b59fedbb258db5a41044fb5";
  };
  patches = [
    (fetchurl {
      url = http://ftp.debian.org/debian/pool/main/s/ssmtp/ssmtp_2.61-12.diff.gz;
      sha256 = "2eb5b2af76d220f14e5133ec4078bab531209fb2f9f8f4e780a0ab8de4818d39";
     })
  ];
  configureFlags = "${if tlsSupport then "--enable-ssl" else ""}";
  postConfigure = "
    sed -e '/INSTALLED_CONFIGURATION_FILE/d' \\
        -e 's|\\(DSSMTPCONFDIR.*\\).(.*)\\(.*$\\)|\\1/etc/ssmtp\\2|' \\
        -e 's|\\(DCONFIGURATION_FILE.*\\).(.*)\\(.*$\\)|\\1/etc/ssmtp/ssmtp.conf\\2|' \\
        -e 's|\\(DREVALIASES_FILE.*\\).(.*)\\(.*$\\)|\\1/etc/ssmtp/revaliases\\2|' \\
        -e \"s| /lib| $out/lib|\" -i Makefile
    substituteInPlace ssmtp.c --replace gnutls/ openssl/ --replace openssl.h ssl.h
    substituteInPlace Makefile --replace /usr/lib/libgnutls-openssl.so -lssl
  ";
  preInstall = "ensureDir $out/lib";
  installTargets = [ "install" "install-sendmail" ];
  postInstall = "install ssmtp.conf $out/etc/ssmtp ";
  buildInputs = stdenv.lib.optional tlsSupport openssl;
}