pgp versions

I would like to use PGP on multiple platforms, and am unsure of which version I should use to maximize my interoperability with other PGP users. In the PGP documentation, "hmiller@lucpul.it.luc.edu" is listed as a source of info regarding the availability of PGP for various computer platforms. I EMailed Mr. Miller but recieving no response. Finger indicates he hasn't used that account in over a month. John Draper suggested I contact you. I am unable to read PGP2.23 files created under DOS on the Macintosh running MACPGP2.2. I saw nothing in the "newfor23" file to indicated that the PGP file format had been changed so as to be incompatible. Are you familiar with this problem? Is there a MACPGP2.23 in the works? -bh