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Everything was working fine, no changes to DNS or Email Server settings. Then we got the error below when some users (not all) send emails (some user and domain names and ip's have been changed).

This happens to some email users only.

De: MAILER-DAEMON [mailto:MAILER-DAEMON] Enviado el: lunes, 25 de junio de 2012 01:49 p.m.
Asunto: Undelivered Mail Returned to Sender
This is the mail system at host

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

The mail system

<>: host[] said:
554-Transaction failed (id=4FE8B30610BE0008), maximum 8 recipients listed
below: Server:999.551.11.130
Command:EODT Error:554 5.7.1 Message refused by DNSBL check.
/ 555.111.2.52 This email has been rejected. The email message was
detected as spam 554 Transaction failed (in reply to end of DATA command)

What could be the source of the error?

share|improve this question
Hating to state the obvious, but the problem is that some of your users' emails are being rejected as spam. "For further assistance, please send mail to postmaster" seems like a helpful suggestion. Ask them why they're rejecting your emails as spam, and then correct the issue. – HopelessN00b Jun 28 '12 at 15:49
up vote 8 down vote accepted

Your ip seems to be in a blacklist server... Check your ip here.

It says so in the return message...

EODT Error:554 5.7.1 Message refused by DNSBL check.

Hope this helps.


share|improve this answer
To be more precise, Spamcop has the ip you tried to use listed. Check here also... – Heishiro Mitsurugi Jun 28 '12 at 15:47

Possible scenarios:

IP has been included in a Real-Time Blacklist due to there is Spam coming from your Domain.
You Domain/IP has been blacklisted by the recipient.

Appliances are scanning Outbound Spam and Spam Filters are updated.

  1. Follow the standard recommendations for SMTP validations on your DNS records: implement Reverse DNS and Sender Policy Framework.

  2. Make sure your internal Network is not compromised by making sure Local Antivirus are installed and updated.

  3. Make sure your Firewall only allows connections on port 25 for your AntiSpam or Email Servers.

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protected by Michael Hampton Aug 26 '14 at 16:20

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