Recently there have been noticed a sudden surge in Jabber/XMPP spammers activity. Spammers not only manage to send a regular messages to users, like this:
but also a some kind of announcement message, each of which opens in a separate window, which is frustratingly annoying. Here is one of such windows:
It is been suggested by a user here, that these are just a regular messages, but with a
subject. Is there a way to disable such messages server wide?