anchor.diff:    };
   
     nativeBuildInputs = [ pkgconfig ];
  -  buildInputs = [ coreutils db openssl pcre perl ]
  -    ++ stdenv.lib.optional enableLDAP openldap;
  +  buildInputs = [ coreutils db openssl perl pcre ]
  +    ++ stdenv.lib.optional enableLDAP openldap
  +    ++ stdenv.lib.optionals enableMySQL [ mysql zlib ]
  +    ++ stdenv.lib.optional enableAuthDovecot dovecot;
   
     preBuild = ''
  +    ${stdenv.lib.optionalString enableMySQL "PKG_CONFIG_PATH=$PKG_CONFIG_PATH:${mysql}/share/mysql/pkgconfig/"}
       sed '
         s:^\(BIN_DIRECTORY\)=.*:\1='"$out"'/bin:
         s:^\(CONFIGURE_FILE\)=.*:\1=/etc/exim.conf:
  
positive.code:       ${stdenv.lib.optionalString enableLDAP ''
          s:^# \(LDAP_LIB_TYPE=OPENLDAP2\)$:\1:
          s:^# \(LOOKUP_LDAP=yes\)$:\1:
          s:^# \(LOOKUP_LIBS\)=.*:\1=-lldap:
        ''}
        #/^\s*#.*/d
        #/^\s*$/d
  
negative.code: { coreutils, db, fetchurl, openssl, pcre, perl, pkgconfig, stdenv
  , enableLDAP ? false, openldap
  , enableMySQL ? false, mysql, zlib
  , enableAuthDovecot ? false, dovecot
  }:
  
  stdenv.mkDerivation rec {
  