Adam Katz wrote:
For what it's worth, I reconfigured my greylisting relay from a blanket delay to delaying only spamcop neighbors, anything that hits a DNSBL, and any Windows *desktop* (using p0f). The move reduced the fatal delay of 80-90% of my incoming mail down to 64%, which is pretty reasonable given the fact that the inconvenience
Some implementations, postgrey for example, keep a whitelist of servers known to retry, so once a small number of mails (3 by default iirc) have been successfully delivered from a given server (or servers in the same /24 subnet), it is auto-whitelisted on the basis that there is little point continually greylisting servers that you *know* will retry anyway.
This approach works extremely well and after a few weeks normal usage very few legitimate mails are delayed by greylisting.
