I installed GrowlMail successfully on my old 2001 PowerBook (after a bit of faffing about) and I love it.
I tried to install it on my Dual 1.8GHz G5 but when I run the .pkg it gives me the error "GrowlMail cannot be installed on this computer Please quit Mail before installing this package".
I've tried quitting Mail first. I've tried running the Terminal commands first too, but neither works.
Any suggestions? Can GrowlMail be installed on G5s?
Unfortunately, the script that checks if Mail.app is currently running is not very clever. Please make sure that you there's no process running which has "Mail.app" in its name. This includes terminals whose current working directory is e.g. /Appliations/Mail.app.