Paul Howard
sme is designed to not accept mail sent to invalid users, just let it do it's job.
Why would you want to play around with mail sent to people who don't even exist ?
I think the reasoning behind your "automatic spam detection" idea is flawed.
If you setup mailrules or similar to redirect all mail (for the now valid but non existent user) to the LearnAsSpam or similar folder, then even legitimate type mail from legitimate senders will gradually get identified as spam, which will impact upon mail sent to all other valid users. Result is that users will start to see more and more legitimate mail being identified as spam and moved to the junkmail folder.