Communication Email Sending Fails with SMTPDataError (553) – Sender is Not Allowed to Relay Emails

ERPNext
, , ,
1

I am encountering an issue when sending emails from the Communication DocType in ERPNext/Frappe. The Communication record is created successfully, but the email fails to send and the following error is displayed:

smtplib.SMTPDataError: (553, b'Sender is not allowed to relay emails')

The email remains unsent, and the Email Queue is not processed successfully.

Could anyone help identify:

  • What causes this SMTP relay error?

  • Whether it is related to the configured sender email address or SMTP authentication?

  • Any required Email Account or SMTP server settings to resolve this issue?

Any guidance would be appreciated. Thank you.

2

which email provider are you using?

some more screenshots/tracebacks/error logs would help narrow down the problem