how do I setup exchange using DynDns?

I currently have a sbs2003 running exchange 2003.  I'm at home using your DHCP comcast network. In my router I have already setup DynDns and I'm able to access my network from the outside world using the domain name they sold me.  I have my mx record  hosted by  I wish to create a connection from the internet world to my exchange server 2003 and vise vesa.  How do I do it? Getting a static IP address is not a option!
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Alan HardistyCo-OwnerCommented:
Please have a read of the following article: 

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You've already done most of the work.

Your last step is to set the "MX" record on your domain at GoDaddy. In the GoDaddy DNS Control Panel, remove any existing MX records and add just one, which points to your DynDNS domain. The priority in this instance doesn't matter, but a value of 10 would be normal.

Ensure port 25 is open through your firewall to your Exchange Server and allow plenty of time for DNS propagation to take place.

Outbound email on a dynamic address is always going to be difficult, since you usually fail to pass the Reverse DNS and blacklist checks at the major ISPs. This is understandable, since the majority of spam is sent from dynamic addresses. The simplest method around this is to relay all outbound email via a trusted smart host - such as your ISP's SMTP server.

timarnold000Author Commented:

I don't understand: (The simplest method around this is to relay all outbound email via a trusted smart host - such as your ISP's SMTP server.)

How would you set this up?

There's essentially two ways to send email out to the Internet.

The first is to have your server directly connect to the recipient's server (such as Gmail or AOL's servers) and deliver the message. This is the usual method, but most major hosts will check a variety of factors to determine your reputation. On a dynamic IP, you can almost guarantee your reputation will be very low and a lot of messages will be rejected.

The other method is to relay outbound emails via another SMTP server - such as one at your ISP. Thus it is the ISP's reputation used in the email delivery process and you can almost always guarantee the email will be delivered. If running on a Dynamic IP, sending email out this way is almost a requirement.

Simon has a good guide describing how to set the latter up using a Send Connector -

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