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#5.7.1 smtp;501 5.7.1 <x@glsfreight.com>...Sender IP must resolve

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#5.7.1 smtp;501 5.7.1 <x@glsfreight.com>...Sender... - 28.Aug.2007 11:27:11 AM

Showaski39

Posts: 27
Joined: 25.Jul.2007
Status: offline

An employee send an e-mail out today to two different recipients. But it could not send to one of the recipients. It came back with a NDR from System Administrator.

Here is what the error said:

"Your message did not reach some or all of the intended recipients. For assistance, contact your system administrator.
<EPSVR3.energyplanning.lcl #5.7.1 smtp;501 5.7.1 x@RetroFitting.com... Sender IP must resolve>"

All help would greatly be appreciated. I'm getting a little frustrated with this because we have been lately getting similar NDR's. Not to many, but a few.

We are running Exchange Server 2003 on Windows Server 2003. Our ISP is Deltacom and they host our e-mail (@retrofitting.com). We are hosting the e-mails on our Exchange server. MX records are set right, mail.retrofitting.com points to our Exchange Server.

Could the recipients mail server be mistaking us for spam and denying us? Again, all help is appreciated.

Thanks,

Joel

< Message edited by Showaski39 -- 28.Aug.2007 12:33:51 PM >

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RE: #5.7.1 smetp;501 5.7.1 <x@glsfreight.com>...S... - 28.Aug.2007 11:32:34 AM

ACH

Posts: 85
Joined: 13.Oct.2006
From: Chicago IL
Status: offline

The error message 'sender IP must resolve' suggests that you need a reverse DNS (PTR) record.

(in reply to Showaski39)

Post #: 2

RE: #5.7.1 smtp;501 5.7.1 <x@glsfreight.com>...Se... - 28.Aug.2007 12:24:37 PM

Showaski39

Posts: 27
Joined: 25.Jul.2007
Status: offline

quote:

ORIGINAL: ACH

The error message 'sender IP must resolve' suggests that you need a reverse DNS (PTR) record.

Can you give me a little more in depth details? I have read up on PTR records. But I was unsure if that is something our ISP should setup, or something we need to setup on our side.

We have two DNS's for active directory and such. Do PTR records get setup on the DNS servers? Please explain, I am not a professional. But I do know a lot and I can pick up on things easily because of my computer knowledge.

Thanks,

Joel

Edit: Could the issue be on the sender's computer? Maybe a firewall or something?

< Message edited by Showaski39 -- 29.Aug.2007 8:49:31 AM >

(in reply to ACH)

Post #: 3

RE: #5.7.1 smetp;501 5.7.1 <x@glsfreight.com>...S... - 28.Aug.2007 1:00:16 PM

uemurad

Posts: 8232
Joined: 7.Jan.2004
From: California, USA
Status: offline

The PTR record needs to be configured by whomever is hosting your public DNS records. That could be you, but is more often hosted by an ISP or service. The PTR record uses an IP address as the search item, and returns a FQDN - the opposite of normal DNS requests (search by FQDN, return an IP address).

The receiving system is using this to confirm that messages addressed from your domain is coming from an IP address identifying itself as your domain.

_____________________________

Regards,

Dean T. Uemura
Microsoft MVP - Exchange (2007-2011)
exchangeguy.blogspot.com
uemurad@yahoo.com

(in reply to Showaski39)

Post #: 4

RE: #5.7.1 smtp;501 5.7.1 <x@glsfreight.com>...Se... - 29.Aug.2007 8:42:36 AM

Showaski39

Posts: 27
Joined: 25.Jul.2007
Status: offline

quote:

ORIGINAL: uemurad

The PTR record needs to be configured by whomever is hosting your public DNS records. That could be you, but is more often hosted by an ISP or service. The PTR record uses an IP address as the search item, and returns a FQDN - the opposite of normal DNS requests (search by FQDN, return an IP address).

The receiving system is using this to confirm that messages addressed from your domain is coming from an IP address identifying itself as your domain.

The pointer record points to our Exchange server? RetroFitting should be a FQDN, our ISP is hosting that domain. Perhaps they are referring to our EnergyPlanning domain which is not a FQDN? Does the pointer record need to point to our Exchange Server?

< Message edited by Showaski39 -- 29.Aug.2007 8:50:06 AM >

(in reply to uemurad)

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RE: #5.7.1 smtp;501 5.7.1 <x@glsfreight.com>...Se... - 4.Sep.2007 10:17:49 AM

uemurad

Posts: 8232
Joined: 7.Jan.2004
From: California, USA
Status: offline

The PTR record needs to resolve the public IP address which last handles the message on your side before sending it out to the recipient system. That PTR record should name an FQDN identifying itself as your SMTP domain.

So, to answer your question, it may or may not be your Exchange server's IP address listed in the PTR record. It will be if you are sending messages directly from your Exchange server to receiving systems. If you are NAT'ing through a firewall or router, it may be the public IP address associated with it. If you are sending all your outbound mail through a smarthost, it may be the public IP address associated with that.

_____________________________

Regards,

Dean T. Uemura
Microsoft MVP - Exchange (2007-2011)
exchangeguy.blogspot.com
uemurad@yahoo.com

(in reply to Showaski39)

Post #: 6