how to record that some emails have been read

Hi:
i am trying to write a mail box. my question is how i can record some emails have opened. Could you give me some idea, please.

for example, i got some emails as following:

<a href="email/1">hi<a>
<a href="email/2">hello</a>
.....

Get the message from a mysql table and have a column called read with either a yes or no option.
If its being read then you change the status on opening of the message.
Hope you understand what I'm saying.
Rafiki

Thanks a lot, i do understand what you say.