[pmmail-list] Editing received emails in *.MSG file really not possible?

[Ben Stover]

Occasionally I receive some emails with e.g. an non-expressive Topic/Subject line like "Contact" or
"offer". No, they are not Spam.

I move them to my own archive folders for later re-read.
However when I search later for exactly this msg then it is very difficult to find them among 1000 of emails.

I would appreciate if I could edit the refering *.msg file and put a new Subject line
into it. Unfortunately PMMail does not like this. The new *.msg is rejected.
It seems to me that there is a hash CRC32 value, last update date of the *.mSG file or something 
similar saved in the *.BAG file.

Is there a trick/work around which let me edit a *.MSG file anyway?

Ben