So... I'm *finally* licensed (CFOs can be such a pain), and running 5.0.9, and pretty clearly, it's time to upgrade now to .15.
The question is: how?
More specifically: how do I do an upgrade without a) setting up a whole new machine, or b) overwriting the current program directory, not to mention restructuring any databases that I won't be able to restructure back -- and let's not forget that if I have to back-out, I need to be able to *reprocess* any incoming mail (either from the outside world or from users) that arrives while I'm on the new system.
I'm *really* big on back-out plans, partially from reading Tom Limoncelli's excellent The Practice Of System And Network Administration, which you should run right out and buy, and partially because it's *email* -- the bosses get cranky when email breaks; that's why I'm moving to Zimbra in the first place.
Anyone else out there who's as paranoid as me, and has a good answer here?