Currently, none of the web-based emails, including GMail, Hotmail or Yahoo Mail, offer any kind of delivery notifications or read receipts. Even when you send a message using Microsoft Outlook, Eudora or Lotus Notes (that allow you to request read receipts), the Internet email service would simply ignore the request and you may never get to know if the message was read by the recipients or caught in the spam filter.
There are however two tricks (rather hacks) that will help you track if your web email message was opened or read by the recipients.
The first and easy option is to sign up for a free account on statcounter.com. Goto the install code options, choose invisible tracking button and HTML only counter. Statcounter will now provide you an HTML Image snippet that you have to insert inside the body of your HTML email message.
Don't worry, the tracking image won't be displayed on the recipient's computer as the couter.gif file that gets downloaded on his side will be a 1x1 white image invisible to the human eye. As soon as your friend opens up your email, it will show up in your statcounter logs. You will know the details like date time when the email was opened and the IP address of his computer.
While the above option is easy to implement, it won't work if the recipient has configured his email client to block downloading of images from the internet automatically. In that case, we can try another method which uses the advanced features of Google Analytics, another free software package.
Here's the second approach that involves embedding a tracking code in an external link which will be pasted in your email message. Whenever the recipient clicks on that link, your analytics software will record it implying that your email was read by him.
The advantage of this method is that no image is downloaded on the client's side but it could fail if the recipient doesn't click the hyperlink. So make the link text compelling and interesting enough to tempt him to visit the target webpage.
You can type "email-to-friend_name" as the Campaign Source and "email_subject_date" in the Campaign Medium. Click generate URL and put that in your email message. Now when your friends click the URL, their visit will be recorded instantly.
Not always reliable but it works. And if you are sending the message to multiple recipients, you can change different "campaign source" variable in each of the email message to track their response in a more detailed fashion.
* Is Someone Reading your Email
* How to Insert Images & HTML Signatures in GMail