The way the document looks, it starts with "From..." or at least that's how each day in the log starts. As it worked well with grabbing the date, with $_=~"Sent:", I figured it would work fine to tell if at this point (per domain breakdown) grab everything and put it into a list, until reaching from, in which case it would need to start all over. Maybe I'm misunderstanding the until statement though.
Thanks for the regular expression tip, will put to good use!