Fix dates via IMAP on messages

[David J. Orman]

Hi,

I've got a curious problem. Due to a bad migration many years ago (via maildir cp's) by one of the admins at my ISP, I've got a mess when trying to view webmail. The webmail client (no, this is not something I can change) relies on server-date for email dates, instead of looking at the email headers. The server-based date for the mail is of course the file creation/modification time, and cp -p was not used apparently. 

All of my new mail is fine (I run my mailserver now) but my mail from about 7-10 years ago is all the date of the migration. Is there any program out there that will read the headers of the mail and change the server-date of the files? I've tried imapsync with -syncinternaldate, to see if it read headers, but it doesn't. I just want to be able to run the command on the user/imap server of choice, and have it read all the mail headers, and set the creation dates properly on the mails (all via IMAP). 

Any help would be much appreciated!
David