Distro: Linux Mint Cinnamon

I use a different Browser and hence uninstalled firefox. But it still receives updates through the system, same with thunderbird. My upgrade manager flags them as security updates sometimes, so I install them. But are they actually necessary? Can I make my system filter them out when updating, or is that a bad idea?

Solution: run dpkg -l "*firef*" to find there were still firefox packages installed. Removed them. Hopefully did the trick.