And be careful of doing this

Oh I'm not going ot spam, I'm actually the user that's getting pissed off our company has left groups open and all the spam is now coming through. Our sysadmin that has the ultimate say in the matter says he's got a spam filter in the works and that they need to be open for people outside our company (partners.) In the meantime I'm getting spammed at engineering, internal project names, etc. It's going to those names at several companies on the To: line.
I was just inquiring to see if it's normal. Everywhere else I've worked, internal groups were not able to be mailed to from outside the domain.