Dates – How to Properly Say a Given Day/Date Does Not Exist

To add a contending opinion, I find this perfectly fine:

The event will take place July 1-10, 2011

I would pronounce the relevant portion "July 1st through 10th" or "July 1st through the 10th."

My default reading of that would be that you can deliver the product at any time on the 18th of August, 2011 and still be considered to have met your deadline.

If the deadline were 23:59 August 17, it would have been stated as "(before August 18, 2011)".

I will also note, though, that most people will consider "the end of the business day" rather than "the end of the day" to be the cutoff time, so you might be considered late if you turn it in after 17:00, if that's when your client normally closes their offices.