May 17 06:03:36 zimbra amavis[1421]: (01421-01) Blocked SPAM, MYNETS LOCAL [] [] <"user1"> -> <"user2">, Message-ID: <>, mail_id: cE4nI0mxTWkw, Hits: -, size: 2127, 112 ms

I have researched this issue for two days now and cannot find a solution.
I have 10 domains on this Zimbra server. This is the newest domain added after I upgraded from 6.0.9 to 7.0.1. This only happens when user1 sends mail to user2 but not vice versa. Any help to resolve this would be greatly appreciated.