Sending mail with postfix and cable modem?

[nailbunny]

Ok, here's my setup. I have a box running with Mandrake 7.1, using postfix, and as far as I can tell, everything is configured just peachy. I can use "mail" to send to anywhere on my network, or any other network. I also have a domain name with a valid DNS entry, however because I am not using a static IP, the reverse DNS lookup is only finding the hostname of my cable provider's, not the alternate hostname. Therefore, the only way I've been able to get any mail through from a remote site to my machine is by using the exact cable hostname my connection is using.

Is there any way to correct this so I can use the hostname I have mapped to my machine instead of the preassigned one?

[shaggy112]

I do not know that I totally understand what you are trying to do here, but I will give it my best shot.
From what I can see here, it sounds like if the company hosting your domain name would give an MX record to your mail server, things would be better.
That would simply pipe everything@yourdomain to whatever host that your postfix server is. I would actually use whatever hostname your isp gives you and take that route.
Just an idea.