DropBox problem (i think a bug that needs to be fixed)

I have been trying over and over regarding trying to find out the error regarding dropbox backup not working with latest version ( stopped since upgrading fron v7 to v7.1 ), not started getting thoses error logs regarding email could not be sent, the error stated : frappe.email.queue.flush : {u’xxx@gmail.com’: (554, ‘5.7.1 do_not_reply@company.com: Sender address rejected: Access denied’)}
Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/email/queue.py”, line 297, in send_one
smtpserver.sess.sendmail(email.sender, recipient.recipient, encode(message))
File “/usr/lib/python2.7/smtplib.py”, line 747, in sendmail
raise SMTPRecipientsRefused(senderrs)
SMTPRecipientsRefused: {u’xxx@gmail.com’: (554, ‘5.7.1 do_not_reply@company.com: Sender address rejected: Access denied’)}

so when i searched python script, i understood that this error is he cannot send the email using the user xxx@gmail.com to the email address do_not_reply@company.com and authentication has failed due to this error, and in the mean time it should be the opposite way arround as it should send the email using do_not_reply@company.com to the user xxx@gmail.com , and i have setup only 1 email account that is the default sending that is do_not_reply@company.comand in the dropbox setting i write down in the (Send Notification to : xxx@gmail.com) so why erpnext is putting it the other way around??
Thanks for your help guys

I guess the dropbox backup problem is solved after deleting old dropbox setting ( erasing them in erpnext as integration service) and starting it all over again with new app created in dropbox ( for folder access), but the send to notification in dropbox setting has to be checked
thanks

well today gave me the same error that i explained in my first post here regarding the error report email sending for dropbox backup : frappe.email.queue.flush : {u’xxx@gmail.com’: (554, ‘5.7.1 do_not_reply@company.com: Sender address rejected: Access denied’)}
Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/email/queue.py”, line 297, in send_one
smtpserver.sess.sendmail(email.sender, recipient.recipient, encode(message))
File “/usr/lib/python2.7/smtplib.py”, line 747, in sendmail
raise SMTPRecipientsRefused(senderrs)
SMTPRecipientsRefused: {u’xxx@gmail.com’: (554, ‘5.7.1 do_not_reply@company.com: Sender address rejected: Access denied’)}

Please help
Thank you