[Dovecot] Is it safe to manipulate Maildir files directly?

[David Henkel-Wallace]

Dovecoters,

is it safe to manipulate files in Maildir/xxx directly or will Dovecot become unstable if I don't make these changes by talking to Dovecot and having it make the changes?  (I'm running 2.1.7 under Wheezy, IMAP only)

My specific application: I am running spamassassin and would like users to be able to submit spam (and ham) directly by moving it into special folders.  A cron job can then find it and take action: feed spam messages to the bayesian trainer and then delete them; feed ham messages to the trainer and then move them into ~/Maildir/cur/

Having the cron job find the messages and train spamassassin is no problem.  The question is how to move the messages.  Is it safe to simply rename the files from my cron job?

The dovecot wiki implies that dovecot will notice a change in mtime and deal with it safely.  Am I reading this correctly?  Changing a message flags (i.e. name) and/or directory will change mtime.  

If I have to go through to Dovecot I am afraid I'd need the user's credentials, which is not appropriate.

Thanks!
-d