From Cesar A. K. Grossmann on Thu, 28 Jan 1999
There are a way to sign my communicator mail and news with PGP on Linux?
Probably not in the current code. You could get involved in the Mozilla project (http://www.mozilla.org) and help their open source community add the desired PGP and GPG (GNU Privacy Guard) support.
Personally I prefer to use packages that are written specifically as mail and news readers rather than trying to "drive screws with a hammer" using a browser as a mail reader and news cient.
Of course I could be wrong. I don't use Communicator's mail and news functions. However, I have to assume that you looked at all of the relevant menus and dialog boxes and didn't see any options in their UI. If that's the case it seems very unlikely that there is some sort of "hidden" interface to some "undocumented" features that will give you PGP support.
Of course you best bet would be to ask this question on the Mozilla developers list. They know much more about Netscape's Navigator (and presumably about Communicator) than I will --- and they are the most likely to add the features (assuming that they really aren't there).