re-size images on upload to media library

Hi , I have a live site running with multiple users uploading and adding images to posts , the problem is they are uploading massive images , some up to 7mb each which is taking up a lot of space.

are there any plugins that will resize these images on upload and cut down the file size on the server ?

I have asked that they optimize these images before upload , but they just don’t do it and aren’t very “tech minded” and dont know how to do it. They are uploading images directly from memory sticks which are huge resolutions.

i’ve just installed a plugin to limit the allowed image upload size (a subtle hint), but i know in a few days they will be complaining about it.

how can i make this easy for them ? is anything available plugin wise thats reliable ?