Question : 2 exchange servers for 2 different mail domains accessed by one domain

We have a single domain, domain1. The company has been up and running on this domain for quite some time. Recently, the company decided to purchase another domain name and do business under this name as well. So now they want an exchange server for domain2 but they want it housed in domain1. (they dont want 2 seperate domains).

Is this scenario possible? Can I have users login to domain1 but setup their exchange account for domain2?

What about users who need access to both domain1 and domain2 exchange boxes?

Answer : 2 exchange servers for 2 different mail domains accessed by one domain

then you would need to setup a second mailbox for each of those users
this may make the address book confusing unless you could hide one