Borrowed idea from https://github.com/adipasquale/mbox-sender-frequency
Sample run:
โ ./sender_frequency -threshold 500 -file ~/Downloads/Takeout/Mail/All\ mail\ Including\ Spam\ and\ Trash.mbox
"Amazon.in" <[email protected]>: 703
Groupon <[email protected]>: 741
"Flipkart" <[email protected]>: 729
YouTube <[email protected]>: 598
GitHub <[email protected]>: 1168