How can I tell if email I sent has been read by the recipient?

You want to know if somebody read the email.The quick and best answer is, there is no way to tell for sure if somebody has read your email.

The problem with this request is that not all systems `talk' to each other the same.Computers support many different styles of email and some support multiple email accounts.Often a person will have a hotmail or yahoo email account for playing around on the internet and then use another account for their personal email.At work, the Information Systems Team often has their own email infrastructure that isn't supported on home computers.Because of these differences, it is often hard to tell if an email has been received, opened or much less read.
However, there are several methods you can use to attempt to find out if a person has read your email.Most email programs have a delivery confirmation option that you can choose when sending an email.Without getting too specific with technical terms, not all programs support the same type of requests.So you can check the confirmation option, but the receivers email program may not support that mail feature.

The way delivery confirmation works is your email asks their email to send a reply back to you when they receive the email.Three things need to work here.

1) Their email system supports that feature.
2) Their email system recognizes the request.
3) Their email system is able to answer.

The fact of the matter is that most email clients ignore delivery confirmation on incoming email.
Most often the email server doesn't support that feature, or the user turns off that feature for privacy reasons.Companies that spam people have used this feature to detect valid emails.Hence, a lot of people have turned off this feature.If you haven't turned this feature off, you may want to consider it.

Another option that you may try is `Read Receipt'.This feature asks the user's email to respond with an email when the original email is opened.However, the same weaknesses exist for this feature as delivery confirmation.
You have another option you may try if you are a little more computer savvy.HTML mail can reference a picture from a remote server.In order to save on memory for emails, pictures can be saved remotely and have a link to it that downloads when the email is opened.For example, Bob can send you an email with a picture of his new truck with the image saved on his server.When you open the email, your computer must access his server to get the image.Bob can then check the historical logs on his server to determine if and when you opened the email.

Again there are problems with this feature.Spammers and others have abused this technique so email programs have had to find a way with dealing with them.The best defense is to not download pictures unless the sender is a known entity to the receiver.You can set your email defaults to not download pictures too.And once again, the sender won't know if or when their email was read by the receiver.

To sum up, each technique for checking if the receiver has received and opened the email fails most of the time.This can be by accident or specific efforts were made to defeat these email features.Hence, you do not have a reliable way to check if a person has received and opened the email.

But, if you assume for a moment that a reliable feature did exist on your email to tell if a person had opened your message, you still wouldn't know if they had actually read the email.For instance, some email software opens the email so that a person can look at it before they open it.Hence, it could trigger the feature, but the person has not actually spent the few minutes required to read the email.How many emails have you opened to see what it was and then not read because it wasn't something you were interested in?