Recently, my email notifications stops sending proper email notifications and it sends a Delivery Failure email to my mailbox instead.
This is what I got from sending a test email:
Code: Select all
Could not deliver message to the following recipient(s):
Failed Recipient: [u]my_email_address[/u]
Reason: Remote host said: 550 Authentication is required for relay
-- The header and top 20 lines of the message follows --
Received: from NagiosCentOS6.localdomain ([u]my_mail_server[/u] [[u]my_public_ip[/u]]) by secured200.zonecybersite.com with SMTP;
Wed, 8 Apr 2015 11:19:15 +0800
Received: by NagiosCentOS6.localdomain (Postfix, from userid 48)
id 7D3B24524C; Wed, 8 Apr 2015 11:19:16 +0800 (SGT)
How should I check from here?