Email.py

import sqlite3
import re

conn = sqlite3.connect('orgdb.sqlite')
cur = conn.cursor()

cur.execute('DROP TABLE IF EXISTS Counts')

cur.execute('''
CREATE TABLE Counts (org TEXT, count INTEGER)''')

fname = input('Enter file name: ')
if (len(fname) < 1): fname = 'mbox.txt'
fh = open(fname)
for line in fh:
    if not (line.startswith('From: ')): continue
    #if not (line.startswith('X-Authentication-Warning:')): continue
    #pieces = re.findall('@\S*[a-zA-Z]',line)[0]
    if line.startswith('Author:'):
        pieces = line.split()
        org = (pieces[6].split("@"))[1]
    else:    
        pieces = line.split()
        org = (pieces[1].split("@"))[1]
        
    cur.execute('SELECT count FROM Counts WHERE org = ? ', (org,))
    row = cur.fetchone()
    if row is None:
        cur.execute('''INSERT INTO Counts (org, count)
                VALUES (?, 1)''', (org,))
    else:
        cur.execute('UPDATE Counts SET count = count + 1 WHERE org = ?',
                    (org,))
conn.commit()

# https://www.sqlite.org/lang_select.html
sqlstr = 'SELECT org, count FROM Counts ORDER BY count DESC LIMIT 1'

for row in cur.execute(sqlstr):
    print(str(row[0]), row[1])

cur.close()