GreyList Multi Server - Major Issue
I had posted this a few years back in the forum. The issue is with Greylisting and multi servers which causes major NDR’s.
When a email comes in and is blocked by greylist on one server the firewall load balancing may send the request to the other server upon retry.
So if greylist is 3 attempts with load balancing and 2 servers it could potentially hit a total of 6 times.
So even though the sending server sent it 3 times the receiving servers could have it once on one server and twice on another resulting in an NDR (if the sender tries only 3 times)
This is a major issue with us which essentially makes the greylist feature useless.
In a major enterprise environment with multiple servers this limitation would be a major downside for Mailessentials.