RDNS failed in email full header

[Roy Avery]

Why do our incoming email messages have a "RDNS failed" in the header? What can I do to fix this?


---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from senderdomain ([senderIPaddress] RDNS failed) by emailservername with Microsoft
SMTPSVC(5.0.2195.6713);


Thank you.

Roy Avery

 

[Ed Horley]

It means that the mail server tried to do a reverse DNS lookup on the IP
address and there was no PTR record published. For mail servers it is
important that you publish a reverse entry that matches the forward A record
you have published in your zone. Please read RFC 2505 and then RFC 2317.

You can also review my PowerPoint slide deck at:
http://www.sfntug.org/index.php?option=com_weblinks&task=view&Itemid=4&catid=87&id=22
if you want more details about what folks are doing as anti-spam techniques.

So, in a nutshell, publish a Pointer Record (PTR) in the reverse file and
you should be good to go.

Regards,
Ed Horley
Microsoft MVP Server-Networking

 

[Roy Avery]

Thanks Ed.

I'll check out the presentation right away. I have a quick question though, did the RDNS fail
against the sender's IP because the recipient did not have a PTR record, or because the sender did
not have a PTR record?

---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from sender_domain ([sender_IPaddress] RDNS failed) by
recipient_email_servername with Microsoft SMTPSVC(5.0.2195.6713);

It means that the mail server tried to do a reverse DNS lookup on the IP address and there was no
PTR record published. For mail servers it is important that you publish a reverse entry that
matches the forward A record you have published in your zone. Please read RFC 2505 and then RFC
2317.

You can also review my PowerPoint slide deck at:
http://www.sfntug.org/index.php?option=com_weblinks&task=view&Itemid=4&catid=87&id=22
if you want more details about what folks are doing as anti-spam techniques.

So, in a nutshell, publish a Pointer Record (PTR) in the reverse file and you should be good to
go.

Regards,
Ed Horley
Microsoft MVP Server-Networking

Why do our incoming email messages have a "RDNS failed" in the header? What can I do to fix this?


---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from senderdomain ([senderIPaddress] RDNS failed) by emailservername with Microsoft
SMTPSVC(5.0.2195.6713);


Thank you.

Roy Avery

 

[Ed Horley]

It looks like it was because the sender did not have a PTR record.

Regardless, you should make sure you have your set up! It will help you
avoid issues long terms with sending and receiving e-mail from your MTA in
the future.

Regards,
Ed Horley
Microsoft MVP Server-Networking

Thanks Ed.

I'll check out the presentation right away. I have a quick question
though, did the RDNS fail against the sender's IP because the recipient
did not have a PTR record, or because the sender did not have a PTR
record?

---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from sender_domain ([sender_IPaddress] RDNS failed) by
recipient_email_servername with Microsoft SMTPSVC(5.0.2195.6713);

It means that the mail server tried to do a reverse DNS lookup on the IP
address and there was no PTR record published. For mail servers it is
important that you publish a reverse entry that matches the forward A
record you have published in your zone. Please read RFC 2505 and then
RFC 2317.

You can also review my PowerPoint slide deck at:
http://www.sfntug.org/index.php?option=com_weblinks&task=view&Itemid=4&catid=87&id=22
if you want more details about what folks are doing as anti-spam
techniques.

So, in a nutshell, publish a Pointer Record (PTR) in the reverse file and
you should be good to go.

Regards,
Ed Horley
Microsoft MVP Server-Networking

Why do our incoming email messages have a "RDNS failed" in the header?
What can I do to fix this?


---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from senderdomain ([senderIPaddress] RDNS failed) by
emailservername with Microsoft SMTPSVC(5.0.2195.6713);


Thank you.

Roy Avery

 

[Roy Avery]

Thank you very much.

It looks like it was because the sender did not have a PTR record.

Regardless, you should make sure you have your set up! It will help you avoid issues long terms
with sending and receiving e-mail from your MTA in the future.

Regards,
Ed Horley
Microsoft MVP Server-Networking

Thanks Ed.

I'll check out the presentation right away. I have a quick question though, did the RDNS fail
against the sender's IP because the recipient did not have a PTR record, or because the sender
did not have a PTR record?

---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from sender_domain ([sender_IPaddress] RDNS failed) by
recipient_email_servername with Microsoft SMTPSVC(5.0.2195.6713);

It means that the mail server tried to do a reverse DNS lookup on the IP address and there was
no PTR record published. For mail servers it is important that you publish a reverse entry that
matches the forward A record you have published in your zone. Please read RFC 2505 and then RFC
2317.

You can also review my PowerPoint slide deck at:
http://www.sfntug.org/index.php?option=com_weblinks&task=view&Itemid=4&catid=87&id=22
if you want more details about what folks are doing as anti-spam techniques.

So, in a nutshell, publish a Pointer Record (PTR) in the reverse file and you should be good to
go.

Regards,
Ed Horley
Microsoft MVP Server-Networking


Why do our incoming email messages have a "RDNS failed" in the header? What can I do to fix
this?


---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from senderdomain ([senderIPaddress] RDNS failed) by emailservername with Microsoft
SMTPSVC(5.0.2195.6713);


Thank you.

Roy Avery

 

[Simon]

If you have Trend IMSS with SPS with reverse lookup checking configured. It
inserts "RDNS Failed" into the header.

Cheers
Simon
---

Thank you very much.

It looks like it was because the sender did not have a PTR record.

Regardless, you should make sure you have your set up! It will help you
avoid issues long terms with sending and receiving e-mail from your MTA
in the future.

Regards,
Ed Horley
Microsoft MVP Server-Networking

Thanks Ed.

I'll check out the presentation right away. I have a quick question
though, did the RDNS fail against the sender's IP because the recipient
did not have a PTR record, or because the sender did not have a PTR
record?

---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from sender_domain ([sender_IPaddress] RDNS failed) by
recipient_email_servername with Microsoft SMTPSVC(5.0.2195.6713);



It means that the mail server tried to do a reverse DNS lookup on the
IP address and there was no PTR record published. For mail servers it
is important that you publish a reverse entry that matches the forward
A record you have published in your zone. Please read RFC 2505 and
then RFC 2317.

You can also review my PowerPoint slide deck at:
http://www.sfntug.org/index.php?option=com_weblinks&task=view&Itemid=4&catid=87&id=22
if you want more details about what folks are doing as anti-spam
techniques.

So, in a nutshell, publish a Pointer Record (PTR) in the reverse file
and you should be good to go.

Regards,
Ed Horley
Microsoft MVP Server-Networking


Why do our incoming email messages have a "RDNS failed" in the header?
What can I do to fix this?


---------example-------------
Microsoft Mail Internet Headers Version 2.0
Received: from senderdomain ([senderIPaddress] RDNS failed) by
emailservername with Microsoft SMTPSVC(5.0.2195.6713);


Thank you.

Roy Avery