Don't you hate it when you send an email and you don't get any response (did the recipient even read it)? Instead of responding with "Why didn't you read my email" isn't appropriate, try to send an update with new information.
Photo by Asta.
Over at The Muse, they give the example of a boss who ignored an email about a flight delay and how to tactfully reinforce the information the boss ignored:
In the case of the examples above, you could try, "New information from the airline: flight likely won't take off until morning. Looks like I'll be spending the evening in Chicago," or "Thank you for sending your phone number; could you also send an updated address when you get the chance?" Keep it as short as possible (one or two lines, so nothing can be missed), while politely reiterating what you need.
Check the link for other ideas on how to handle difficult email situations.
How to Respond to Cryptic Emails [The Muse]