You will get your "read receipt" when I am ready to reply to your email.
There is absolutely no reason you need to know on an individual email-by-email basis when someone has read an email. If you're an email marketer, try Constant Contact, Mail Chimp, or ExactTarget. It's not the 90s. If you're just sending personal emails to people, don't worry. Your email will be sent successfully (unless you're a spammer -- and if that's the case you've got other things to worry about). And I will read it within hours of you sending it.
In fact, most people with smartphones (and over 300 million smartphones shipped last year) read emails within minutes of receiving it. And those who don't have push email notification systems (either on their computers, smartphones, or tablets) still check their email every 30-60 minutes. According to one poll, about 67% of people surveyed said they checked their email more than 6 times per day, and nearly 10% of those check email more than 40 times per day.
So I am begging you people, please stop requesting read receipts!