anchor.diff:          s:^\(EXTRALIBS_EXIM\)=\(.*\):\1=\2 -lpam:
           s:^# \(EXTRALIBS_EXIM\)=.*:\1=-lpam:
         ''}
  +      ${stdenv.lib.optionalString enableSPF ''
  +        s:^# \(SUPPORT_SPF\)=.*:\1=yes:
  +        s:^# \(LDFLAGS += -lspf2\):\1:
  +      ''}
         #/^\s*#.*/d
         #/^\s*$/d
       ' < src/EDITME > Local/Makefile
  
positive.code:     ++ stdenv.lib.optional enableLDAP openldap
      ++ stdenv.lib.optionals enableMySQL [ mysql.connector-c zlib ]
      ++ stdenv.lib.optional enableAuthDovecot dovecot
      ++ stdenv.lib.optional enablePAM pam;
  
    preBuild = ''
      sed '
  
negative.code: , enableMySQL ? false, mysql, zlib
  , enableAuthDovecot ? false, dovecot
  , enablePAM ? false, pam
  , enableSPF ? true, libspf2
  }:
  
  stdenv.mkDerivation rec {
  