Well, some say so. Greylisting (detailed at Greylisting.org) is a spam prevention technique for mail servers. The concept is simple:
– When your mail server receives a message from a new sender, the server temporarily rejects the message with a “try again later” or “delay” message.
– Most outgoing mail servers (senders) will indeed try again. Sometimes this doesn’t occur for a while, though. 15 minutes, 30 minutes, a hour….longer.
– When the message is sent again, it’s cleared and delivered to the user.
Most spammers don’t get this option. Spammers are smart, though! They know this trick. So, was this ever a good idea? Maybe. Is it useful now? I say no.
Disable Greylisting on Mac OS X Mountain Lion Server
Open Terminal on your server and execute the following command:
sudo serveradmin settings mail:postfix:greylist_disable = yes
You can restart the Mail server, as needed.
You’re done. Comment here if you have any challenges using this command.