I am confused as to how everything ties together with regards to having sn SME box available to bot intranet & internet(and other remote access).
Firstly, i have everything setup at a local level to a point that is great.  
Intranet:
-Users can use email/webmail locally.
-www.mydomain.com redirects to 
http://servername.
-putty works to ssh in.
-dyndns setup so that mydomain.homelinux.com shows 
http://servernameInternet/remote:
i have registered 
www.mydomain.com with a registrar, and can now login to modify dns records and setup hosting.
-people seem to be unable to see "mydomain.homelinux.com" or the ip address to go with it (dynamic dns through isp).
-havn't configured mydomain.com dns records.  what dns records do i use?  since its dynamic over isp, i assume this might not be possible since dns would constantly be changing... so then:
-what external email server would i use?
Any help would be appreciated.  I'm a little confused right now,  but so far, SME Server has been absolutely fantastic.
Cheers.