Exchange 2010, SMTP Reverse DNS Mismatch
Hi Expert,
There is a domain that queue inside my server, unable to send out, there is an error while i check their inbound traffic through exchange test connectivity, but when i use yahoo,gmail send, is working.
After that, i use mxtoolbox to check my mx record, i get this,
SMTP Reverse DNS Mismatch Warning - Reverse DNS does not match SMTP Banner
could it cause the email not able to send out because of this warning ? and how can i fix this warning.
Thanks
There is a domain that queue inside my server, unable to send out, there is an error while i check their inbound traffic through exchange test connectivity, but when i use yahoo,gmail send, is working.
After that, i use mxtoolbox to check my mx record, i get this,
SMTP Reverse DNS Mismatch Warning - Reverse DNS does not match SMTP Banner
could it cause the email not able to send out because of this warning ? and how can i fix this warning.
Thanks
A reverse dns is handled by your Internet Provider. Basically your email server will use an internet line which will have an IP address (i.e. 8.8.8.8). This IP address will resolve to a hostname (i.e. google-public-dns-a.google
What the error is refering to is that the reverse dns hostname does not match the FQDN of your email server (the SMTP banner). Your banner may be set to mail.domain.com but the reverse dns may be set to randomnumber-isp.com or something like this. Many email servers are configured to suspect this to be possible spam.
You need to contact your ISP and get them to change the hostname of your IP address to match the SMTP banner/fqdn of your mail server. Note some ISP's do not have this facility, in which case you may need to use a smarthost service or change ISP's.
What the error is refering to is that the reverse dns hostname does not match the FQDN of your email server (the SMTP banner). Your banner may be set to mail.domain.com but the reverse dns may be set to randomnumber-isp.com or something like this. Many email servers are configured to suspect this to be possible spam.
You need to contact your ISP and get them to change the hostname of your IP address to match the SMTP banner/fqdn of your mail server. Note some ISP's do not have this facility, in which case you may need to use a smarthost service or change ISP's.
Services like MXToolbox are testing your receive connector for this test. Ignore this result!
If you want to test what your send connector is set to, follow the instructions at http://cbl.abuseat.org/helocheck.html to send an email and you will get a response showing the info.
At that point you can test for a match between the SMTP banner on the send connector and your PTR record by typing something like the following (using an example where your SMTP banner is set to "mail.domain.com") :
nslookup mail.domain.com 8.8.8.8
The IP from this should match the IP reported in the HELO check email.
And then using the IP that is reported in the HELO check email (substitute for x.x.x.x below):
nslookup -q=ptr x.x.x.x 8.8.8.8
This should give a FQDN that matches the SMTP banner.
If you want to test what your send connector is set to, follow the instructions at http://cbl.abuseat.org/helocheck.html to send an email and you will get a response showing the info.
At that point you can test for a match between the SMTP banner on the send connector and your PTR record by typing something like the following (using an example where your SMTP banner is set to "mail.domain.com") :
nslookup mail.domain.com 8.8.8.8
The IP from this should match the IP reported in the HELO check email.
And then using the IP that is reported in the HELO check email (substitute for x.x.x.x below):
nslookup -q=ptr x.x.x.x 8.8.8.8
This should give a FQDN that matches the SMTP banner.
Ask to service provider to create record for smtp banner with your external domain.
like owa.yourdmain.com
like owa.yourdmain.com
ASKER
Hi Expert,
Thanks for the value advise, in my case, we are renting our server in data center, we manage our own exchange, can the data center help to change the hostname of IP address to match the SMTP banner/fqdn of my mail server?
Thanks
Thanks for the value advise, in my case, we are renting our server in data center, we manage our own exchange, can the data center help to change the hostname of IP address to match the SMTP banner/fqdn of my mail server?
Thanks
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To Configure the smtp banner for the domain you are trying to send from:
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.