Watching an episode of Parks and Recreation on an iPhone in an airport is different from watching it on the couch in your living room. Receiving a tweet when you walk into a store is different from reading a newspaper ad at the breakfast table (okay, that's not a fair comparison since no one reads newspapers anymore).
It's not just where your message is delivered, but when. What frame of mind is the person in? What else is going on around him? With smartphones, tablets and 4G connected laptops, we're receiving marketing pitches 24 hours a day. Just as telemarketers were excoriated for calling during the dinner hour, there are better times than others to deliver your message based on who you're talking to, where you reaching them and what you're selling.
Take a moment to understand the moment before you send out your next communique.