i use gmail, but i use it really poorly. everyone else's gmail inbox that i've seen is super organized and i'm like "EVERYTHING GOES IN THE INBOX, WHO CARES ABOUT ORGANIZATION". i'm most likely to see/remember important emails if they're just in the inbox. i have a chrome extension that tells me when i have an unread email, so i read every single one. the little number that shows up on the icon is annoying and marking as unread is the way to remind myself of things.
about 10k-11k emails in that inbox.