Unable to send email

Unable to send email.
It gives :- smtplib.SMTPSenderRefused: (550, b’From address must match authenticated address’, 'user@privatedomain.com’) .

I had configured the email domain as standard, It is only working for specific one or two users.
And also sometimes emails don’t show up in email queue.
Any assistance would be greatly appreciated.


Similar issue reported here as well. Looks like you are not alone.

I have tried with gmail and got me same thing.

Any solution for that?