Someone here gave good advice that I've been (basically) following since. The advice was something like this:
1) Is there a question? If yes,
2) Does the question need to be answered? If yes, walk away, think about how you want to answer it. If no, file in your archives and forget about it.
I would advice against having his e-mails go straight to trash and delete without reading -- instead, I would set up the rules to have them go to a special archive folder. But that's because I'm dealing with an abusive stalkerish AXH. Just a thought.