askelon
> ...only two (domains) actually have email used on them -
> the others are forwarded at my isp end to other email accounts.
If I guess correctly what you are doing, then it's probably better to setup all your domains on your sme server, and then delegate your mail for certain domains to the external mail server at your ISP, rather than forwarding mail as you do at present.
There are forum posts giving the db commands necessary to delegate mail for certain domains only, so search.
Here is one post
http://forums.contribs.org/index.php?topic=32167.0