Hi,
Emails sent from our server to customers who use messagelabs are accepted by the messagelabs server, but never delivered. This is really dangerous, if an email is not delivered the sending server should be notified of the reason why so the sender knows the message was not recieved.
Here's an example log entry:
2017-03-28 13:11:37 1cspyL-003Zy1-Qc <= sender@domain.co.uk H=mail-pg0-f45.google.com [74.125.83.45] P=esmtpsa X=TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128 CV=no A=plain:sender@domain.co.uk S=4245 id=CADHKSS7LTgDYFzMo8+OeWdiu8D4j1p3RMoSCF2KhCT3W_ihkaw@mail.gmail.com T="Test" from <sender@domain.co.uk> for recipient@depaulcharity.org.uk
2017-03-28 13:11:38 1cspyL-003Zy1-Qc => recipient@depaulcharity.org.uk<recipient@depaulcharity.org.uk> F=<sender@domain.co.uk> R=lookuphost T=remote_smtp S=4368 H=cluster8.eu.messagelabs.com [85.158.139.19] X=TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256 CV=yes C="250 ok 1490703098 qp 31506 server-6.tower-178.messagelabs.com!1490703098!83424282!1"
I've checked at http://ipremoval.sms.symantec.com/lookup/ and I'm seeing the following message:
The IP address 164.132.254.220 was found to have a negative reputation. Reasons for this assessment include:
- The host has been observed sending spam in a format that is similar to snow shoe spamming techniques.
Our server is not on any blacklists and has a good reputation with Cyren (http://www.cyren.com/ip-reputation-check.html) and Cisco Senderbase (http://www.senderbase.org/lookup/?search_string=16...).
Please provide us with more information so we can resolve this situation asap. This is costing us and our clients money!