Warning - Reverse DNS does not match SMTP Banner

fabzster · **Joined:** Tue Aug 07, 2012 1:21 pm **Posts:** 0

Hi

I am new to the forums.

I seem to also have this error:

220 mail.pinnaclemarketing.co.za Microsoft ESMTP MAIL Service, Version: 6.0.3790.1830 ready at Tue, 7 Aug 2012 21:25:14 +0200
Status Result
OK - 41.134.193.26 resolves to 41-134-193-26.dsl.mweb.co.za
Warning - Reverse DNS does not match SMTP Banner
Warning - Does not support TLS.
0 seconds - Good on Connection time
OK - Not an open relay.
7.114 seconds - Warning on Transaction Time
Session Transcript:

220 mail.pinnaclemarketing.co.za Microsoft ESMTP MAIL Service, Version: 6.0.3790.1830 ready at Tue, 7 Aug 2012 21:25:14 +0200 [0 ms]
EHLO please-read-policy.mxtoolbox.com
250-mail.pinnaclemarketing.co.za Hello [64.20.227.133]

I would really appreciate the assistance

brian@mxtoolbox.com · **Joined:** Tue Feb 03, 2009 1:52 pm **Posts:** 10

Warning - Reverse DNS does not match SMTP Banner
What does Warning - Reverse DNS does not match SMTP Banner mean?

The short answer is that the reverse IP address name is not contained in the server HELO or EHLO banner. In the example below, the string “someotherdomain.com” is not found anywhere in the server banner, which is reporting “example.com“. This is only a warning, and in some cases you may have no control over this. However, if you have the ability to make these match, you should. Some mail servers look for this and use it to mark messages you send as questionable. Most mail systems will not reject your messages outright, but this may effect your spam score increasing the likelihood your messages will be marked as spam.

In other words, it is a best-practice you should endeavor to follow. It doesn’t mean you are a bad person or won’t be able to send email.

220 mx.example.com StrongMail SMTP Service at Wed, 09 Sep 2009 17:00:01 -0700

Not an open relay.
0 seconds - Good on Connection time
0.156 seconds - Good on Transaction time
OK - 1.2.3.4 resolves to mail.someotherdomain.com
Warning - Reverse DNS does not match SMTP Banner

If you are not sure where to access your SMTP banner in your mail server, read below for some helpful hints. We do not advise making ANY changes to your mail server if you are not the system administrator or confident in making these changes.

Configure SMTP banner Exchange 2003

1. Open Exchange system manager.
2. Expand your administrative group (”First administrative group” by default).
3. Expand Servers.
4. Expand "YourServersName".
5. Expand Protocals container.
6. Select SMTP container.
7. On the right window, right click the Default SMTP virtual Server (Or the name you set your SMTP Server) and select Properties.
8. Select the Delivery Tab.
9. Click the Advanced button.
10. Under the Fully Qualified Domain Name (FQDN) type mail.yourdomain.com (The A/Host record you created in DNS for your mail server)
11. Click Apply and OK again to accept the changes

Configure SMTP banner Exchange 2007/2010

1. Open the Exchange management console.
2. Select the Organisation Configuration container.
3. Select Hub Transport container.
4. On the right select the Send Connectors tab.
5. Right click your send connector and select properties.
6. On the General tab under the Set the Fully Qualified Domain Name (FQDN) this connector will… type the A record domain name you created. Which in our case is mail.yourdomain.com. Click OK.
7. Under the Server Configuration container click the Hub Transport container.
8. In the Right window Select the properties of the Receive Connector under Receive Connectors tab.
9. On the General tab under the Set the Fully Qualified Domain Name (FQDN) this connector will… type the A record domain name you created. Which in our case is mail.yourdomain.com. Click OK.

Sendmail (instructions from here)

1. Open /etc/mail/sendmail.mc
2. Change the line
define(`confSMTP_LOGIN_MSG', `hexemail.yourdomain.com')
the should match exactly the same as what you see in the mxtoolbox,
220 hexemail.yourdomain.com ESMTP
3. Compile sendmail.mc
m4 sendmail.mc > /etc/mail/sendmail.cf
4. Restart Sendmail

To verify these changes we would recommend using our SMTP Diagnostic Tool again.

Let me know if you have any other questions or concerns.

Thanks,
Brian

BuggzieM · **Joined:** Thu Aug 09, 2012 12:37 pm **Posts:** 0

Excellent steps for Exchange Server 2010 connector configuration. This assisted in correcting the rDNS issue but required a phone call to ISP.

My configuration:
GoDaddy hosted A & MX records setup.
ISP provided IP block /24
A (Host) mail = 98.189.xxx.xxx - One IP from block pointing to internal Exchange Server 2010 configured as HUB Transport Server
MX (Mail Exchanger) = Priority 0 Host @ Points to mail.myweburlname.com
-------
Exchange Server 2010
Configured OC Hub transport and SC Hub transport as above for FQDN mail.myweburlname.com
After changing the FQDN in OC/SC Hub transport required correcting the IIS certificates.

Had to remove Send Connector & Receive Connectors\Network\Enable Domain Security (Mutual Auth TLS) checkmark? Not sure why.
----
Called ISP asked to update rDNS for IP number to say mail.myweburl.com
---
Leaves me with the minor issue “Warning - Does not support TLS.” Will work on the encryption and SSL certificates another day.

rDNS is now working
Thanks for the helpful information on rDNS

ARR · **Joined:** Wed Mar 06, 2013 5:47 am **Posts:** 0

Hi

Can anyone explain why the RDNS lookup would work sometimes but not others? If I put my IP in and test sometimes everything runs through correctly and if I try again it will fail the RDNS check.

Thanks

Alan

peter@mxtoolbox.com · **Posted:** Wed Mar 06, 2013 7:55 am

If you want to either post your IP or email me an offline message with your IP I would be glad to look at it for you.

mfhache · **Joined:** Tue Apr 02, 2013 7:31 am **Posts:** 1

I am having a similar problem with "Warning - Reverse DNS does not match SMTP Banner".

Currently I am running exchange 2003 and am hosting my own internal DNS but have an external DNS hosted by NetworkSolutions.

There is an MX record in my NetworkSolutions page as well as my internal DNS but I continue to have this problem. I followed the instructions listed above to adjust my FQDN on the exchange server but I am still getting the above error. Does this take time to propagate or is there something else?

My mail server is mail.pacex.com. (There is also a legacy.pacex.com that resolves to the same box. We are in the transition from 2003 to 2010).

brian@mxtoolbox.com · **Joined:** Tue Feb 03, 2009 1:52 pm **Posts:** 10

I apologize for the delay in responding to you regarding "Warning - Reverse DNS does not match SMTP Banner". It appears as though your issue has been resolved, probably due to propagation.

http://mxtoolbox.com/SuperTool.aspx?act ... n=toolpage

SMTP Reverse Banner Check OK - 72.38.117.99 resolves to mail.pacex.com

Thank you for using the tools at mxtoolbox.com.

Brian
MxToolbox Support

Warning - Reverse DNS does not match SMTP Banner

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