This has been an issue for a client of mine. Apparently even if you select release by mail, and let it send to the original recipient, it doesn't work. Well this product is VERY picky. While it stores quarantine items by display name, it cannot release them by that same name. This actually is pretty bad if it's sent to a huge list of people. It needs fully qualified email address in order to release. Below are the steps to make it work.
1. Open the quarantine.
2. Right click the item and select release by mail.
3. Uncheck the box to “Send to original intended recipient(s)”
4. Check the box for “Send to the following”
5. Type in the full email address of the recipient you wish to release it to.
6. Click OK.
7. Refresh the quarantine, the time should no longer be listed.