I like to think about emails for a little while before I reply to them. I've also been busy lately, so if I don't reply right away, I'm not ignoring you. In general, I'm fairly difficult to offend, so if we've exchanged a cordial email or two, don't worry that I'm ignoring you because you offended me.

Sometimes the little while I spend thinking about an email before I reply becomes a longer while, as I'm terrible at keeping track of time. If you feel neglected, it might be a good idea to remind me about you. Emails like "Hi Stabbity, Haven't heard from you in a while, just wanted to see how you're doing. "  will be responded to cheerfully, if not always promptly - sometimes I do get really busy.