Postgrey is aPostfix policyserver thatimplementsgreylisting.When a requestfor maildelivery isreceived byPostfix viaSMTP, thetripletCLIENT_IP /SENDER /RECIPIENT isbuilt. If it isthe first timethat thistriplet isseen, or if thetriplet wasfirst seen lessthan 10 minutesago, then themail getsrejected with atemporaryerror.Hopefully,spammers orviruses willnot try againlater, eventhough suchbehavior isrequired perRFC.
Luit is afilter that canbe run betweenan arbitraryapplication anda UTF-8terminal emulator. Itwill convertapplicationoutput from thelocale'sencoding intoUTF-8, andconvert terminal inputfrom UTF-8 intothelocale's encoding. It ismainly used tosupport xterm.