Lately I'm finding myself further delaying the answering of questions I receive through e-mail (from people I don't know) by responding to them, some two+ months old, with, "Are you using the latest version of the plugin?" or "What's the address of your site? Let me take a look." Sometimes I'll just flat-out say, "Have you resolved the issue since you wrote me?" Best case, they have answered their own question and I can take it off my plate. Worst case, I have another couple of weeks to give a substantive response to their original e-mail.
For the e-mails that don't contain questions, it's now not uncommon for me to reply with a simple "Thank you" or "Good point," whereas five years ago I probably would have engaged the writer much more and attempted to enter into some sort of sub-surface dialog.
Horrible, I know, but desperate times…
At least I haven't declared e-mail bankruptcy.