Here are some items I think would be of value to the product.

Activity Log

Either color coded text in the Activity log to differentiate the rejected spam from successfully sent mail or the ability to toggle show/hide successful delevered mail.

Ability to freeze scrolling so you can read the text of a particular email attempt.

Quarantine

Icons to differentiate the Deliver Selected vs Delete Selected buttons.

Invert Selection would be handy.

Ability to toggle between an auto-refresh feature (at user set intervals) or manual refresh in the quarantine window.

Refresh with newest quarantined email at the top, having to see the old mail first and scrolling down at each refresh is cumbersome

A field with why the message was quarantined.

Push-buttons to add a quarantined email sender, ip etc to the white list.

Statistics

More stat choices that would help identify spammers who are repeat offenders.

Stats on source IP and domain in rejected email would be useful.

Settings

The ability to toggle filters, MAPS server, IPs, domains , etc like you can do with countries would be interesting (but not as much as the items above).