There are some programs like Group Mail Plus that will check an email address to see if it is functioning. It is not free, and may be a little costly for a would-be stalker.
Speaking of which....
We don't support such activities as stalking. Please do not continue along this line of posting.
If you can't stop stalking and need help, I suggest that you find some support group or submit yourself for some psych evaluation. Thread closed.
Dave