Make SBS 2008 accpet more than remote.domain.com address?

In your external DNS for domain2.com create an A record for remote and point it to the external IP address (same as remote.domain1.com)

if you want to be able to accept email for domain2.com then you will also need to configure an MX record and an accepted domain in Exchange Management Console under Organisation configuration.

It depends what you are trying to do?

But there is no A record for external IP for domain1. There is only CNAME because he uses only DynDNS.

The cname will be referencing an A record somewhere.

No CNAME is referring to moba.dyndns.tv (for example) of course there is an IP address but it changes a lot and that's way the DynDNS is being used.

Then for the second domain create the same cname record this will do the same job.

However a better solution would be to upgrade to a business class DSZl solution with a fixed IP address then these issues will go away.

It is very costly to have real IP address. Also I tried to do what you said to create CNAME in the domain2 but I faced the following:
1- when I type in IE remote.domain2.com it doesn't redirct me to HTTPS.
2- when I type Https I get a message saying that access denied or something like that.

Thank you.