Alright, I've been using the greylisting feature for about a week now and it's working very well. However, I would like to make a couple suggestions:
1) Change the Manage Greylist pages, for both pending and rejected, to have the list sorted by date - preferably received, but at least one or the other because it's hard to manage, especially the rejected page, since the messages don't seem to be in any discernible order from what I can tell. This would make it much easier to organize the list by pages and tell what day you're on and see if you need to approve any emails that were rejected.
2) One other thing I would like to see for either of the greylist management pages is the subject line of the email if that is possible. I realize that the object is not to download the entire mail to prevent the mail system from consuming resources, but the subject line would be very helpful in determining if the email may or may not be legit in case we don't know the sender, and since the IP address doesn't help very much in this instance either.
3) I think it would also be very helpful to incorporate a whitelist button within the Horde Inbox console, like there is for the Held Mail console. This way a user can whitelist email addresses permanently that might have gotten stuck in the graylist, and not have to go to the options, SpamCop tools, etc. every time a user needs to add to the list.
That's all for now. Keep up the great work!