Tag: Correctly

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

MY LIFE AND OTHER HARD TIMES IN THE TEXAS HILL COUNTRY ...

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.

Did You Know That There Are Many Famous People With ADHD Who Have Lead Productive Lives?

Qoʻqon UZ - Dakhmai-Shokhon 05

Yes, there are famous people with ADHD. Some have long since passed on into history but they have left their mark and we benefit from their contributions to the world and to society. Others are easily recognizable and are to be found in the acting and sports arenas, business world, etc. While there is still a stigma attached to anyone with a mental disorder it is worthwhile letting your child who has been diagnosed with Attention Deficit Hyperactivity Disorder know that they actually share the spotlight with some very notable and noteworthy individuals. Some have even gone so far as to suggest that schools display information in the form of posters regarding those celebrities and other famous people who have or had ADHD in a bid to eliminate the stigma associated with the disorder.

There are around ten million adults in the United States living with Attention Deficit Hyperactivity Disorder or ADHD. Given the enormity of this number it really should come as no surprise that a significant number of those who are famous for whatever reason should also be included in that figure. When this disorder is not treated the individual will suffer with poor concentration and will struggle with being organized which can understandably lead to greater problems in the person’s life.

Roughly sixty percent of children in the country who are diagnosed with ADHD will continue to experience the associated symptoms even once they have attained adulthood. Alarmingly many children who are ADHD will remain undiagnosed with a number of them only getting diagnosed once they have reached middle age.

For children diagnosed with this disorder famous people with ADHD can really help them to cope better as they recognize themselves in these celebrities. For example the Olympic swimming champion, Michael Phelps has ADHD and he has been reported as saying that he oftentimes felt stigmatized while he was growing up. This was exacerbated by the fact that he had to collect his meds from the school nurse every day until eventually he convinced his mom to let him go off the medication. He used his competitiveness in the swimming pool to help him focus himself and attributes that with learning to manage his Attention Deficit Hyperactivity Disorder. In fact it has been shown that ADHD kids very often benefit from participating in competitive sports.

Other famous people with ADHD include actors and actresses such as: Whoopi Goldberg, Tom Cruise, Will Smith, Dakota Fanning, Robin Williams, Sylvester Stallone, Jim Carrey, and so many more. Of course years ago it was not possible to diagnose ADHD and so there are many people in history who are believed to have had the disorder based upon written documentation that exists. Some famous people in history who are believed to have had Attention Deficit Hyperactivity Disorder include Pablo Picasso, Alexander Graham Bell, Albert Einstein, Walt Disney, Christopher Columbus, Mozart, and Beethoven.

Having Attention Deficit Hyperactivity Disorder is no reason to feel ashamed or inferior. In fact if your child has been diagnosed with the disorder it might be a good idea to let them discover just how many well-known and influential people have as well. When it comes to treating the symptoms of this common childhood disorder there are generally two schools of thoughts. One advocates the use of ADHD medication to control the symptoms while the other suggests a more natural approach involving dietary changes and homeopathic remedies. Considering the fact that many of the drugs used in treating the disorder are known to be rather dangerous and with harmful side-effects it is certainly advisable to consider the natural approach as your first course of action. By changing the diet of the ADHD child it has been shown to greatly improve the symptoms, allowing the child to function better and lead a normal and productive lifestyle. Teaching the child relaxation techniques as well as helping them to focus on some activity, such as a sport they enjoy, can greatly benefit them and help them to live life to the full.

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

The pond

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

~ Wonderful Pretty Mansion ~

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

paradise of ducks

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

L1070163

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.

Configure Exchange E-Mail Server Reverse DNS and MX Records Correctly

St Augustines Londonderry

If DNS is setup incorrectly, over time your mail server IP will be added to blacklists. Nowadays most E-Mail servers have some kind of spam protection service which in turn means that all your inbound mail will be blocked if you do happen to be listed on a spam blacklist.

In this article I will describe how to correctly configure your MX and reverse DNS records for your mail server. This article is based on an Exchange 2003/2007 server but every other messaging server will follow the same principle.

Assigning an IP address

Starting from the bottom up the first thing you need to do is assign a static external IP address to the internal private address of your mail server. You will need to apply these rules on your firewall to port forward SMTP (port 25) and NAT an external IP address to the internal address of the server.

Something that a lot of administrators forget to do or check is to set the outgoing NAT rule to use the same external IP address created for the inbound rule to the mail server. If this isn’t set, Reverse DNS will not match and in turn your mail server will be listed on blacklists. If your firewall rules are setup correctly the IP address listed on this page should be the same IP address you mapped to the internal private IP address of the mail server.

Create the MX records for your mail server

For the purpose of this example, listed below are all the details of my mail server to help you understand what you need to do.

External IP: 87.22.1.22

E-Mail Domain: domain.com

You will need to be an administrative contact for your External DNS provider for your domain to make these changes. In most cases this can be done through an online control panel through your DNS provider. Failing that on the phone or via E-Mail.

1. The first thing we need to do is create an A record to point to the external IP address mapped on your firewall to the mail server. The host A record can be called any thing but is commonly called “mail”. In our example we will create “mail.domain.com” to point to IP address “87.22.1.22”

2. Next we will create an MX record to point to the newly created A record of our mail server.

Within your DNS control panel select “add MX record”. Make sure that the host address is the root domain name in our case “domain.com”

Set the FQDN as the A record we just created which in our case is “mail.domain.com”.

The lowest property is the most preferred but in our example we will set the priority as 10.

Use NSlookup to check DNS and MX records are applied

It can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To check our DNS entries are applied and correct we can use nslookup.

1. Open a CMD prompt and type nslookup

2. Type set type=mx

3. Type the domain name which in our case is domain.com.

In our example the output should read as follows if correctly setup:

> domain.com

Non-authoritative answer:

domain.com MX preference = 10, mail exchanger = mail.domain.com

mail.domain.com internet address = 87.22.1.22

Configure Reverse DNS

Reverse DNS is used to verify that the mail server is who it says it is. The recipients mail server will do a reverse lookup to make sure that the IP address of the mail A or host record in DNS is the same as the IP address it is communicating with. Only 1 RDNS entry can be present per IP address.

To do this you will need to contact your ISP to make this entry. You will not be able to do this in your DNS control panel unless your ISP also host your DNS and give you the functionality to add your own RDNS records.

In our case we would contact our ISP and advise that we would like to create an RDNS entry for our IP address 87.22.1.22 which would resolve too mail.domain.com.

Verify Reverse DNS

Again it can take up to 48 hours for DNS to propagate but in most cases 12-24 hours. To verify that the RDNS entries have been added and are correct do the following:

1. Open a CMD prompt.

2. Type Ping -a 87.22.1.22 (This is the external IP address for your mail server. In our case we use our external IP address stated above)

If RDNS is configured correctly the following output will be shown:

C:UsersUser>ping -a 87.22.1.22

Pinging mail.domain.com [87.22.1.22] with 32 bytes of data:

SMTP Banner

Every time a mail server establishes a connection with your mail server it shows its SMTP banner. This banner must be resolvable on the internet and best practice is to have it as your mail host/A record.

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 YourServerName.

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 type mail.domain.com (The A/Host record you created in DNS for your mail server)

11. Click OK 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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.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 FQDN this connector will… type the A record domain name you created. Which in our case is mail.domain.com. Click OK

To verify these changes we can use telnet to view the output upon establishing a connection on port 25 to our mail server. Use the following steps to do this:

1. Open a CMD prompt

2. Type Telnet mail.domain.com 25.

The output you see should look something like this and contain your A record of your mail server:

220 mail.domain.com Microsoft ESMTP MAIL Service ready at Sun, 28 Feb 2

010 17:51:20 +0000

If you use an edge server or a SPAM filter appliance like a Barracuda the SMTP banner will have to be set on this device/server.

Check to see if your mail server is on spam lists and/or an open relay

A great website to use to check your MX records, RDNS, check if your mail server is an open relay and check to see if you are listed on spam lists is www.mxtoolbox.com. This is a great site and one to keep in your favourites.

Following these guide lines will successfully and correctly configure mail routing to and from your mail server. The next step is too secure and ensure your mail server is not an open relay. I will be writing a separate article dedicated to this in the near future.