import pandas as pd
USERS = pd.DataFrame({'email':['a@g.com','b@g.com','b@g.com','c@g.com','d@g.com']})
print (USERS)
email
0 a@g.com
1 b@g.com
2 b@g.com
3 c@g.com
4 d@g.com
EXCLUDE = pd.DataFrame({'email':['a@g.com','d@g.com']})
print (EXCLUDE)
email
0 a@g.com
1 d@g.com