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Have any about a Delivery Status Notification (Failure) code 501

We are receiving the following delivery status notification when we are sending e-mails to a specific domain, let's say domain.com.
The error message is:
"The following recipient(s) could not be reached:
Krrrrr@domain.com on 10/23/2008 12:07 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mail.mydomain.com #5.5.0 smtp;501 Failure Bad FROM MX record (cached), Setting G_BADFROM_NOIP> "
I have to specify that we are using our own smtp server (not ISP's server) that is behind a FW in DMZ, while our domain DNS records are administred by our ISP. Have you any ideea about this DSN error?

Karl12347

It looks like your exchange server is having problems communicating out to the internet. make sure you have host A records for you ISP service provider in your DNS and also that the correct MX records are in you dns.

Hope this helps.
Karl

Shyjin Varaprath

* Does the Reverse DNS lookup work??

https://www.experts-exchange.com/questions/22847385/NDR-5-5-0-smtp-551-on-Exchange-03.html

Hope this helps (^_^)

stefan75

ASKER

In fact we are sending external e-mails using a GFI server (in DMZ). Exchange is used only as a local mailserver that is forwarding the external messages to the GFI server. We are receiving emails using another server (an external one), which for the MX record is setup correctly in our DNS. The A and MX records are correctely setup in our DNS. Reverse DNS lookup is setup to point to our smtp (outbound) server that is different then our MX (inbound) server. We're receiving the specified DSN error only when we're sending emails to one particular domain (but we care receive e-mails from it).

ASKER CERTIFIED SOLUTION

Karl12347

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