Is there any update on this? Is there any plan for another method of exempting a whole SMTP cluster from Greylisting other than by manually adding lists of IPs?
We`re recently dealing with some clients that use a mailing system from OVH.net and their servers are really bad at handling Greylisting - if they receive the try again later message, their mailing system will cycle through dozens of gateways like 1.mo1.mail-out.ovh.net, 9.mo1.mail-out.ovh.net, 2.mo1.mail-out.ovh.net, 15.mo1.mail-out.ovh.net, 3.mo167.mail-out.ovh.net and so on and so on, each time with increase lag between tries. This causes huge delays in email delivery for clients that use OVH. We`ve tried whitelisting the IPs that we see in our SMTP logs, but almost each time they use another server and they have lots of them. We`ve also not been able to find any IP lists or IP ranges that they use, so this is getting out of hand.
Implementing a check based on SPF or something like that would be a business and life-saver - this could be seen as a basic feature that should go with Greylisting.
Looking forward to any updates on this.