Trevor is a freelance writer covering topics ranging from the Android OS to free web and desktop applications. When he is not writing about mobile productivity, He is coaching and playing the world's greatest game... Soccer.
In your Gmail, all you have to do is to enter the term size:10mb in the search box and all emails larger than 10MB will show up in the list. You can change the number to reflect the size you want to filter.
This is so far the easiest way to filter your emails by size.