DNS issues with existing email server

I want to keep the current server used for my email because it goes through an antispam service provider.

The problem is the antispam provider configures by the IP of my mail server, ie all processed mail on my account is delivered to that IP.

So if I switch to dreamhost, the MX will have to be set to the antispam providers MX, but dreamhost will some how have to retrieve my mail from my current mail server.

Can DH be configured that way?

I am also thinking whether it will be possible to keep my current DNS but configure the *.domain.com to point to DH DNS, so that all the explicit ones to be handled by my current DNS.

Will that be an effective option?

[color=#0000CC]The mental attitude whose nature is resolution is but one in this world, o son of Kuru[/color]