I don’t “get” people who don’t answer their email in a timely fashion. While not all email requires a response, when it does, it ought to be done sooner — say a few days as opposed to several weeks, months, etc. — rather than later.
Having the ability to dash off a quick note to a friend is the major point of email.
Even if you’ve been asked a question you can’t yet answer, write and say so. It’s the voids that are found in cyberspace that are most annoying. If I’ve taken the time to write because you’re my friend or family, you can take 2 minutes to write back. I don’t care who you are… Nobody is sooooo frikkin’ busy that they can’t take 2 minutes for an email… even me.
If you send me spam, now that’s a whole other rant.