DynDNS Mailhop Services

16 04 2008

Setting up SBS 2003 for DynDNS Mailhop Relay and Mailhop Outbound

As there are no formal instructions for this procedure, I’ve put this together as a personal record for myself as to how I got it working.  Feel free to use it however you like.

These directions assume you already have your server on the internet with a static IP or a custom DNS dynamic service from DynDNS.com and a full qualified domain name

I apologize for the bad images.  I had to shrink them to fit.  If you click on them, you will see a higher resolution version of each pic.  I also created a PDF so you can see the whole document and print it.  The PDF is available here:

Printable Version with Pictures

Mailhop Relay



Incoming (port 587)
Set up in DynDNS Mailhop Relay:

So the ‘yourdomain.com’ is where you put in your servers domain.  By that, I mean that if you go to a computer off the SBS network and open Internet Explorer and type in www.yourdomain.com into the address bar, it will open up the remote web workplace into the browser of your SBS.  Unless of course you’ve disabled port 80 on your SBS.  But regardless, the url you put in the ‘Destination Mail Server” should bring the world right into your physical machine that is right there in the room with you.


Open port 587 in SBS Firewall:
Assuming you are NOT running ISA Server, follow these directions to open port 587 (or any other port)
If you are running ISA, you will have to find those steps on the internet since I haven’t gotten that far in my server setup yet.
Open server management Start->All Programs->Administrative tools->Server Management
Click ‘To Do List”
Next to “Connect to the Internet” Click Start
Click next until you get to the firewall page and select “Enable Firewall”
Click “Add”
Enter a service Name: SMTP Relay
Select: TCP
Port: 587



Set up Exchange:
Open Exchange System Manager Start->All Program->Microsoft Exchange->System Manager
Open Servers->’server’->Protocols->SMTP
Right Click “SmallBusiness SMTP Connector” and select Properties


Click Advanced then in the next window, Click Edit.
Enter the New port number to listen for incoming mail: 587


We’ll be back to this area in a moment to set up outbound but for now, just “OK” yourself back to the Exchange manager screen.


Stop and Restart the SMTP Service found under Start->Administrative tools->Services


That should do it.  Try sending some mail to yourself from an outside email address like yahoo or hotmail.

If it doesn’t work right away, it may just be a matter of waiting until the DNS and MX records catch up. 

Mailhop Outbound

Okay, this was a little tougher to figure out.  Basically I searched for directions online setting up a Smart Host with Exchange server 2003 and tried different settings from different directions until everything worked.


So obviously, you must purchase the Mailhop Outbound service for your domain.



Set up Exchange:
Open Exchange System Manager Start->All Program->Microsoft Exchange->System Manager
Open Servers->’server’->Protocols->SMTP
Right Click “SmallBusiness SMTP Connector” and select Properties



Click the ‘Delivery’ tab and select the button labeled ‘Outbound Security’

Select the option ‘Basic authentication (password sent in clear text)’
Input the user name and password you use to access your DynDNS account online

Here I notice I have TLS selected and in another place I don’t.  I don’t think this is necessary to make it work but I’m not changing anything at the moment since its working.

Click ‘OK’ then select outbound connections.

Okay, here is where you change the port if your ISP is blocking your OUTBOUND port 25.

To check this, open a command prompt on the server.

C:\>telnet outbound.mailhop.org 25

Here my ISP is blocking outbound 25:

 If you get this error, try changing the port to 2525 or 10025 (both of these are also used by DynDNS for Mailhop Outbound along with port 25):

C:\>telnet outbound.mailhop.org 2525

Now I get:

Now, once you found a port that gives a response enter it in the TCP port: box .

Click ‘OK’ then click the ‘Advanced’ button.

Put your servers public domain name in the box labeled ‘Fully-qualified domain name’
If you click ‘Check DNS’ you should see a message that the domain name is valid.
Enter ‘outbound.mailhop.org’ in the ‘Smart host:’ box.


Click ‘OK’ twice until you’re back to the Exchange Server Manager

Now open the connectors folder
Right click ‘SmallBusiness SMTP Connector’ and select properties

In this first window, select ‘Forward all mail through this connector to the following smart hosts’
Enter ‘outbound.mailhop.org’

The server name should already be input in the box below.


Select the ‘Advanced’ Tab
Click the ‘Outbound Security’ Button
Select ‘Basic authentication 9password sent in clear text)’ option
Click the ‘Modify’ button
Enter your user name and password you use to access the DynDNS website


Click ‘Ok’ until you’re back to the ‘Advanced’ tab.

Select ‘Request ETRN/TURN when sending messages’
Select ‘Issue ETRN’
Click the ‘Domains…’ button
Click add and select your domain from the list.



Click ‘OK’ twice until your back to the ‘Advanced’ tab

For consistencies sake, I noticed that I had an extra entry in the following location.  I don’t think this is necessary but I’ll show you in case it is.

It is under the ‘Address Space’ tab.  I added my domain explicitly along with the default wild card.

Click ‘Add’
Select ‘SMTP’ and click ‘Okay’
Enter your Email domain and click OK.


Click ‘OK’ to close the properties window and test sending an email to an outside address.

Before I test outgoing:

After I send a message from an Outlook user, it sends it to the queue:

Finally, after exchange sends it to the DynDNS outbound service:



Well, that’s what worked for me.  Admittedly, I wrote this after I spent three days working on the issue so I could have forgotten a setting but I don’t think so.  If you have any problems or comments, email me at roland@csipc.net. After all it works now!




14 responses

24 11 2008

This solution worked. I tried others and they were incomplete. I followed the April 16, 2008 posting even though it was for SBS. I used this for Exch2k3 except for the firewall portion. It seems duplicative but it all is necessary including the ETRN items. Be sure to restart the SMTP virtual server at the tail end of the alterations.

4 01 2009

congratulation !!! very nice tutorial 😀

19 01 2009
John Haroian

Excellent tutorial. It worked very well for my SBS 2003 installation. Thanks for posting!

16 09 2009

Please advice if this works on exchange server 2000

I tried telneting port 25 , 2525, or 10025 but i got this error

could not open connection to host on portf 23: connection failed

16 09 2009

I have not tried this on Exchange 2000. The principle should be the same but the windows will probably look different.

23 09 2009

Does anyone have the directions for use with Exchange Server 2007? There is a big difference between 2007 and earlier versions. I’m able to get mail from outside sources, but when I send outside the firewall using port 587 the mail never makes it to recipients… not returned either… limbo I guess. Pardon my ignorance on the subject matter, I’m not an Exchange guru obviously…lol

Thanks and have a great day!

23 09 2009

If your port 25 is blocked, you neet to use the mailhop outbound type service. Mail servers by default listen on port 25. Mailhop outbound listens on different ports (587, 10025, etc) They take your outgoing mail and forward it on using port 25.

The directions above that deal with the DynDNS site would be the same for 2007. As for the step by step exchange 2007 directions, I have not set that up with Mailhop Outbound so I’m not sure.

Actually I use a corporate account now with an open port 25 so I don’t use the Mailhop services anymore but I’m happy these directions have helped others.

20 03 2012

Some times its a pain in the ass to read what website owners wrote but this internet site is real user friendly!

14 01 2013
Pierre-Yves Andri

This helped me a lot to reconfigure my old SBS 2003 server, since there is no more tutotials available on DynDNS (too bad).

May I signal some point : at STEP 3 (incoming mails) the SmallBusiness SMTP Connector should not be mentionned, but well the regular SMTP virtual server (screenshot is ok).

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