First, an answer to the following ppl:
to fpi (and everyone else) sorry - this may not be strictly perl related. it didnt occour to me on the first post, as cgi nearly always equals perl in my mind.
to athomason, thankyou! that was exactly what I was looking for. Until I thought about it a little more.

Now for everyone else:

I am attempting to write a webmail program to check pop mail from any server. The question is secuity and (now) how to implement sessions. I have everything working as planned. I store a cookie with the session number and write a file for each session on the server containing the users details. It occured to me much later, that I cannot see a way to delete these files automatically, assuming the user does not click 'logout'.
I would prefer not to use SQL or anything complicated to make it possible to install on (almost) any server. I have been racking my brains about it, and I think there is probably no solution but to use a database. And even then I will have to find out if a database can do it. What do fellow monks think?
Thanks!