well, i don't use it on my mac, but i do use it on my work laptop running xp pro.
pgp does have settings for mail and aim clients. i'd guess that it had an uninstall program you should have used rather than just delete the app - especially for an app that has to be that embedded in your system.
maybe try reinstalling and checking for an uninstaller. if that doesn't work or that option doesn't exist for you, either try an uninstaller like "appzapper" or do a search for all files on your system with pgp in the name.
if they look like they belong to pgp, move them to a folder somewhere, and ideally note down the path you moved them from so you can put them back if you experience problems. keep those files for some time - if you experience no issues for a few weeks at least and through a restart or two, you should be ok to delete them.