Take a look at www.mandrill.com Free for up to 12000 emails a month. They act as your smtp server, and can embed tracking codes for you (amongst other services). I'm very happy with them.
What sort of tracking? Tracking clicked links? (Can be done with many link shortening services) Tracking email open rate or spam rate? (Can be done in the options of many autoresponders)
A tracking link can be as simple as: <img="http://mywebsite.com/images/1x1pixel.gif"> HTML: When the email is opened, the email runs over to your website to download the 1x1 pixel graphic, which of course is just a single pixel, and can't be seen by the reader - but now your website can count how many times this image is requested. This is the basic fundamentals of email tracking. You'd do best to have an Autoresponder company handle such requirements though...
Dear Methebest, Someone also recommended mandrill.com, which is associated with mailchimp. May I know the difference between Mandrill.com and Mailchimp?
I thing the following link perfectly answers your question. http://kb.mailchimp.com/article/mandrill-for-mailchimp-users