Filters (whitelist, blacklist, perhaps groups) should be checked prior to accepting new messages

I was typing a message into a whitelist GA, when GA creator temporarily removed me from his whitelist. When clicked submit, I was brought to the page stating I was not on GA creator's whitelist, however later when he added me again, it turned out that my message was still posted successfully.
While it is not a typical use case, I consider it as a bug.