Over the past few months, I have received complaints from a small percentage of users about unreceived email. All indications point to a greylisting problem. In particular, mail from Exchange 2003 servers and Hotmail/MSN seemed to be primary culprits in that they do not resend the original message after greylisting sends a busy. Of late I have noticed that gmail is doing the same thing.
Recently, I deleted the greylisting databases and restarted the greylisting system, but received even more complaints. One heavily affected user was receiving none of the email from maxell.com.
I pursued the possibility of an Exchange-related problem with David Schweikert (author of Postgrey), but he said that I was running the latest version and that any Exchange problems he was aware of were resolved many years ago.
As of yesterday, I have turned greylisting off and do not wish to leave it this way for long. My data suggests that greylisting reduces my SPAM by approx 600,000 messages per year.
I need definitive help with this and have been a paying customer for many years. Please formulate a resolution plan that does not necessitate many loops of forum communication.