To give a top level overview of what we're trying to achieve.
Company1 is merging with Company2.
Both company's use Exchange 2003 and hosted services for filtering e.g Mimecast.
There will be a new email domain setup mergedcompany.com that we need users in both firms to be use as their primary smtp address.
Company1 will be using Mimecast to accept inbound/outbound mail and company2 will be getting rid of their hosted filtering solution.
First of all we want to put in new MX records for mergeddomain.com to point to Company1 mimecast service so it can accept mail.
The mail will then be routed to Company1 Exchange organisation and from there to Company2's Exchange organisation.
Now at the moment there are no trusts in place but this will be done in the near future.
Also looking at Quest's collaboration services to do GAL/freebusy sync across the 2 Exchange organisations in the 2 forests.
Just looking for advice on the best way to go about getting this all in place.
Is it even possible to do this across 2 Exchange organisations sitting in 2 separate forests?