I guess it had to happen sooner or later. Twenty minutes ago I received the first bounced spam message. Some MTA informed me that it had no user named 'mark' and that it was sorry it couldn't deliver the message.
Both the 'Return-path' and the 'From' fields were forged and pointed to a made-up chongqed.org email address. The spam is spamvertizing various geocities URLs. Those URLs look like random garbage to me (e.g. 'hvabbsct' and 'yyyobzjtb').
The geocities URLs deliver horribly broken HTML that always redirects to analmaturehardcore.com.
Currently, the rate of incoming bounces is rather moderate. I 'only' received twenty bounces in those twenty minutes. I will have to see whether I can keep the catch-all account activated.
In case you're wondering: Of course I reported all those geocities URLs to Yahoo's abuse department.
I just received a response from Yahoo! Customer Care. Over one month after I sent the complained. And it was an automated response. This sucks.