Do you happen to use that account for mailing lists at all ? If it was a *true* catch all account then you would probably have a lost more SPAM in it
With respect to the second email you have posted then my assumption would be that the spammers are attempting to poison your Bayes. If the SPAMs are always from the same email address then you have two choices 1) Create a custom SA rule based on the address and score high 2) Have a look at the blacklist section in
Improving Anti-spam system - Zimbra :: Wiki