I go to shaw webmail - at the bottom it shows you how man...

[SJW]

I go to shaw webmail - at the bottom it shows you how many MB you've used.  

[mdk]

Use the "search" function, to search on a simple word, such as "the".  Don't worry if you get "zero results".

Then, down the left, under "Advanced Filters", there is a "Size" option. Click on "Size", and choose "larger than 100 Kilobytes. Don't worry if you again get "zero results".

You will see something like:

Click on the "X" to the right of the word "the", to rerun the modified search.

What you should see is a list of all "large" messages in ALL folders.