I’ve been running gld for more than two months now and it is truly efficient. The current statistics say:

`# of entries in the database         : 16077

of one hit entries in the database : 15100

Oldest entry in database             : 65 days ago `

This means that almost 94% of the attempts to send mail through my server are only made once!

Unfortunately Facebook and Google Mail do not play well with greylisting, as attempts that are told Service temporarily unavailable, please try later by greylisting are very likely to be retried from a different IP. I’ve made a little script that scans /var/log/mail.log for such mail servers and add them to the gld whitelist table.