holy geebus, what was the total size of those 496 images? In future I would recommend to zip those files into 1 file.
most likely it's freezing because it's trying to retrieve the data for all those 496 files from the email server
can you disconnect from internet and check if it still freezes? if not then you'll have to find a way to delete the files from the server or let your computer just sit some day for a while to try to get those 496 images loaded...