I have merged both your posts as I suspect they are related.
The email notification would be because somebody posted on a thread that you had started.
There are a few reasons that you are unable to access the thread with the link in the email.
It is not unknown that "old" notifications are resent for some reason.
It could be that the thread has been moved to an archive area of the forum that is only available to the forum moderators.
It could be that the thread for some reason has since been deleted.
As regards your question about how to see your old threads. Click on your username and this will open a list of all your posts that are still able to be accessed.
