in reply to
Point me in the right direction - Monitor a Mulicast IP address or stream
From one new person to another, the first suggestion I would have is that whenever you wonder 'can I do X..?' -always go to search.cpan.org first and search for modules there with good keywords. I have not done all of what you are asking to do with Perl, but I have monitored packets with nmap. Anyways, I have emailed from Perl on many occasions quite successfully with MIME::Entity and MIME::Lite. I personally prefer to use the former. Both of those module's documentation can be found on CPAN. Searching 'IP packets' at CPAN yielded the module NetPacket::IP as the first result. So that may be a good place to start.
If you are using Active State Perl, I suggest running 'ppm install <module-name-here>' on any of those to get you started.