Outlook plugin

I've SEP 12.1 RU2 with Outlook plugin (enabled in Outlook 2007 client and via policy).

I've received a .zip attachment that was not blocked by the plugin.

If I extract the content, SEP (not the plugin but the normal SEP) block the content (virus, autoprotect).

If I try to forward the message, newly no block.

The message with its viral content, starts.

I thought Outlook Plugin should block the attachment. Am I wrong?

Exchange server, if it's important to know.