Remote host said: 550 Authentication is required for relay
Problem reported by Parinda Dissanayake - 1/5/2016 at 5:56 AM
we install new mail server with with smartermail free gateway server and we are migrating domains one by one to our smartermail server.
all the websites hosted in rackspace and it related to travel operation so all the booking related mail sending through this 3rd party smtp host smtp2go(smtpcorp) authenticated account so they confirm each and every mail delivery to costumer mail boxes but all the mails receiving from this web server through smtpcorp to our server getting below error
-----Original Message-----
From: System Administrator
Sent: Tuesday, 5 January, 2016 03:59
To: enxxx@mabuhaytravel.co.uk
Subject: Delivery Failure
Could not deliver message to the following recipient(s):
Failed Recipient: conxxx@mabuhaytravel.co.uk
Reason: Remote host said: 550 Authentication is required for relay

-- The header and top 20 lines of the message follows --
Received: from gate.forward.smtp.iad3a.emailsrvr.com (gate.forward.smtp.iad3a.emailsrvr.com []) by MailEdge01.mabuhaytravel.co.uk with SMTP;
Mon, 4 Jan 2016 19:59:25 -0800
Return-Path: <enxxx@mabuhaytravel.co.uk>
X-Spam-Threshold: 95
X-Spam-Score: 0
X-Spam-Flag: NO
X-Virus-Scanned: OK
Authentication-Results: smtp11.gate.iad3a.rsapps.net header.DKIM-Signature=@smtpcorp.com; dkim=pass
X-MessageSniffer-Scan-Result: 0
X-MessageSniffer-Rules: 0-0-0-2945-c
X-CMAE-Scan-Result: 0
X-CNFS-Analysis: v=2.1 cv=IvInLtPg c=1 sm=0 tr=0 a=JWuGvDRtfE5H3m2vv7NRDg==:117 a=JWuGvDRtfE5H3m2vv7NRDg==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=hMgq8R9AAAAA:8 a=mD95u9NkAAAA:8 a=kj9zAlcOel0A:10 a=3DwXih_bWBFMlAarP_wA:9 a=y-ecAZeJ--Ih2UrT:21 a=eyU3lFpbL3MUcy-H:21 a=CjuIK1q_8ugA:10
X-Orig-To: fares@tcukmail.co.uk
X-Originating-Ip: []
Received: from [] ([] helo=a0i218.smtpcorp.com)
by smtp11.gate.iad3a.rsapps.net (envelope-from <enxxx@mabuhaytravel.co.uk>)
(ecelerity r(42060/42061)) with ESMTPS (cipher=AES128-SHA)
id 79/7D-23214-89F3B865; Mon, 04 Jan 2016 22:59:20 -0500
We have asked the 3 party service if they are sending mail from a static IP, and so they provide us all the ip ranges
and we enter those to by pass authentication list in the smartermail but still no hope
How do we solved this

1 Reply

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Bruce Barnes Replied
The way to properly resolve this is to enforce the use of SMTP AUTHENTICATION for everyone sending messages through your mail server.
Whitelisting, or bypassing authentication opens you up to becoming an "open relay," and, once discovered, your facilities will be used by every spammer in the world.  They have lists.  They share information, and they pounce on e-mail servers which whitelist large blocks of IP addresses.
Bruce Barnes
ChicagoNetTech Inc

Phonr: (773) 491-9019
Phone: (224) 444-0169

E-Mail and DNS Security Specialist
Network Security Specialist

Customer Service Portal: https://portal.chicagonettech.com
Website: https://www.ChicagoNetTech.com
Security Blog: http://networkbastion.blogspot.com/

Web and E-Mail Hosting, E-Mail Security and Consulting

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