Grey Listing with postgrey
As an email server administrator, the fight against spam is ongoing. For the last two months I have been blocking about 2000 spam messages per day. (only 2 false positives since July 12 2006).
Mostly using RFC restrictions, such as required fqdn in helo etc... The second biggie was finding the right combination of blacklists.
But messages are still getting through at an average of 1 spam per account per week. This is too much. I would like to implement greylisting.
Last night I installed postgrey and I have closely monitored my mail logs, I haven't missed any legitimate emails so far. I am pleased.
Unfortunatly greylisting causes delivery delays, Microsoft mail servers delay an average of about 700-800 seconds.
I understand that postgrey is supposed to white list servers who frequently make it past the grey list. Where can I control these settings?
Next, I found whitelist_recipients in /etc/postgrey. I saw that postmaster@ and abuse@ are whitelisted (which is good). I want to whitelist a single domain on my server, so I tried @thedomain.net. I restart the postgrey daemon, but it still grey lists the domain.
How can I whitelist an entire local domain?
How can I control the threshold to whitelist a particular server?