Sending email via smtplib in Python

Question

I have a problem with sending email via smtplib. I am trying to use company smtp host. I have following example code:

import smtplib
import getpass as gp

sender = '[email protected]'
receivers = ['[email protected]']

message = """From: From sender
To: [email protected]
Subject: SMTP e-mail test

This is a test e-mail message.
"""

pw = gp.getpass('Pass:')
smtp_ip="smtp.company.com"
smtp_port=num

try:
   smtpObj = smtplib.SMTP(smtp_ip, smtp_port)
   smtpObj.ehlo()
   smtpObj.starttls()
   smtpObj.login(sender, pw)
   smtpObj.sendmail(sender, receivers, message)  
   smtpObj.close()       
   print ("Successfully sent email")
except Exception as e:
   print ("Error: unable to send email", e)

After running this I am getting following error

Error: unable to send email {'[email protected]': (453, b'4.7.1 <[email protected]>: Sender address rejected: not owned by user [email protected]')}

I was even using the same address but still there is a problem with this ownership. Have someone any idea what can be wrong here? Thanks in advance.