Yes, it's possible to use Perl to write "contact management" and SPAM software.

No, it's impossible to tell (in any language) if a harvested email address corresponds to a user with a static IP. It's also similarly not really within the realm of possibility to determine the email addresses that are accepted by an ISP in behalf of a particular static IP, regardless of language used. IP's and email addresses aren't really related. But then if your "contacts" have "opted-in" willingly, they could probably tell you at sign-up time what their email address and static IP address are.

It is entirely within the realm of easy Perl-fu to organize "contacts" into groups, and to be able to move things from one group to another.

And it is also possible with Perl, or just about any other language, to handle group-change and opt-out requests.

You could probably accomplish the list management stuff with just about any language; Perl, C, Java, shell-scripts, or even BASIC. If only it weren't so... Ask the Dark Gods for implementation details.

PS: Most "email list" management tools are already built into majordomo software, which is, iteslf written in Perl. You might look into that instead of starting over with your own home-rolled solution. Majordomo is probably the most broadly used emailing-list management software on the net.