I've been running an instance of 7.260 as a secondary production box so it gets some 'real' traffic across it. Since it also receives a fair quantity of email as a tertiary MX it's a good indicator to see whether it's processing emails correctly. I've noticed that 7.260 seems to be letting a LOT of spam through to the mail server whereas it's being captured in the other ASG's running 7.201.
FWIW, spammers like to target secondary and tertiary MX servers as they tend to have less filtering.
Are you sure that it's not just a higher ratio, not that spam which would be caught on 7.20 isn't getting caught on 7.26?
There are ways to 'replay' spam through SMTP as tests. It's kind of tricky with telnet, but can be done. You can't fake the sender's connecting IP though.
