For some reason, a set of my mail folders lost their "courierimapuiddb" files, and now cause errors when one of my mail clients tries to list the folders. There is a file "maildirfolder", as well as directories cur, tmp, and new, and there are messages in some of the folders' "cur" directory. So everything seems to be in place except for the missing "courierimapuiddb" file. The root folder of this set of folders actually has the "courierimapuiddb" file. For example, take a tree of folders rooted at foo. There is a ~/.maildir/.foo/courierimapuiddb, however, in all subfolders such as ~/.maildir/.foo.bar/ that file does not exist. I've looked in some of those files, and it almost seems like I could rebuild them myself, because they're basically a list of messages in the folder. The problem is the first line of those files contains some number whose origin is unknown to me. So, is there some way I can rebuild these files, while preserving the messages in the folders, so that I can use these folders again?

Thanks!