Readability guaranteed + no regex
Code
# Code
```pythondata []
import pandas as pd

def find_valid_emails(users: pd.DataFrame) -> pd.DataFrame:
    
    def find_valid_email(email):
        
        cond_1 = email.count('@') == 1
        cond_2 = email[-4:] == '.com'
        cond_3 = all([ char.isalnum() or char =='_' for char in email[:email.find('@')] ])
        cond_4 = email[ (email.find('@')+1) : email.find('.com') ].isalpha()
        
        return cond_1 and cond_2 and cond_3 and cond_4

    users['valid'] = users['email'].map(find_valid_email)
    return users[users['valid']][[ 'user_id', 'email']]
```
['Pandas']