For a webmail project I am working on, I have been given the task of
decoding OpenMail-encoded e-mail message files dumped from an HP-UX
OpenMail server using the backup function.  The files are oddly
encoded in UUENCODE format and I have had no trouble developing (in
PHP) a way to strip that out.  What follows thereafter, however, is
the "Transaction File" and "Distribution List" sections that appear to
be formed of binary and ASCII and are nearly impossible to decode. 
HP's OpenMail does provide technical documentation on the file format
but matching up the details they provide with PHP's unpack() function
does not appear accurate.  So what I am looking for is a PHP unpack()
format or other method to grab all of the information stored within
these files without extra characters et cetera.

Can you post the dump file? With that I can try out some of my theories. Thanks.

Tox-ga