My filter worked the first time but it now ignores the messages. Why is this?
This is how Vamp is dsigned to work. Otherwise you will get the same message being
processed on every connection. If, however, you do want to do this, e.g. when you are
testing your filters, just change the value of message cache to zero (on Mailboxes tab).
But remember to set it back to a suitable value when you have finished testing.