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Exchange 2013 - Reverse DNS does not match SMTP Banner?

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mxtoolbox gives me some negative points i would like to ask about

im behind Cisco, which doesnt currently support TLS/esmt stuff, will be upgrading OS later. Currently my HELO looks like:

220 **************

ok, for now.

But EHLO is wrong:

EHLO MXTB-PWS3.mxtoolbox.com

250-HOST.mydomain.local Hello [64.20.227.133]

i changed SMTP banner for my receive conector as it was described here: http://brainlitter.com/2013/01/30/how-to-set-the-exchange-2013-mail-headerbanner-for-smtp/

but no luck, it still wrong. And mxtoolbox is givving me:

SMTP Reverse DNS Mismatch Warning - Reverse DNS does not match SMTP Banner

Please what to do?

Thank you

PS. My Default Frontend receive connecter has a field FQDN: Specify the FQDN this connector will provide in response to HELO or EHLO.

and set to host.domain.local

but i cant change it to host.domain.com, getting error

error If the AuthMechanism attribute on a Receive connector contains the value ExchangeServer, you must set the FQDN parameter on the Receive connector to one of the following values: the FQDN of the transport server "HOST.domain.local", the NetBIOS name of the transport server "HOST", or $null.

asked Feb 5, 2015 by Alex  

1 Answer

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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 09 Jan 2016 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

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.
answered Feb 17, 2016 by jt  
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