gmail filters are too limited
I also prefer to use my own filters to have more control over what gets discarded. Google really needs to add wild card capability to filters or at least the ability to filter on @domain instead of the whole address. I get lots of junk mail from foreign accounts that get past the filters simply by changing one letter in the email address. Check the forums and you'll see this request has been out there for a couple years. It's odd that Google has not answered it.