Cracking an archive of old cc:Mail files

I have been given a stack of cc:Mail files with historical, and
possibly legal interest. The family of the owner of the files, who has
deceased, has asked me to investigate the possibility of deciphering
them. All of the individual's usual passwords the the family know have
failed to open it. As best as I can tell, this from INSTALL.TXT in
c:\LOTAPPS, the version is cc:Mail for Windows Release 6.03. I am not
certain whether the files are encrypted, or if they are simply in a
proprietary format. The files have the name MSGxxxxx where xxxxx is a
number with a leading zero. I presume those are the data files. There
are also files in c:\CCMOBILE\CCDATA1.

Any assistance would be most appreciated.

Please respond to me directly or follow up to comp.mail.misc.

MisterFitz