messagerules.plist symlink functionality

I use Dropbox to store app support info for numerous applications. I then use symlinks on each computer to get OSX to look in the dropbox folder instead of whatever the normal local folder would be. I am now trying this with mail.app but am running into odd behavior. I have moved my messagerules.plist file to a Dropbox folder and replaced it with a symlink in ~\library\mail\v2\maildata. This works like a charm for all of the other apps that I have tried, but not so much for mail.app.

Mail.app doesn't seem to work with this file in a way that I think of as normal. Instead of saving the changes to the file, mail.app appears to be writing out a totally new file every time a change is made. It renames the original version with a .backup name and then writes a new plist.

Is that an accurate description of what's happening? It seems an odd method to me and totally breaks the symlink concept. Has anyone had luck wth this or something similar? I am after automated syncing, not simply copying files back and forth. Unfortunately, copying files looks like it may be the only way to do it at this point.

(A google search for the words symlink and messagerules.plist turns up a whopping six hits; one of which when translated from German to English seems to be saying this should work. Unfortunately, that's the only thing I've come up with on that end of things and its not actually working for me.)