Apologies for the title.

We're using Exchange for our email but using Google Apps accounts for Google Drive. We have one domain name for our Exchange system (school.county.sch.uk) and one for our Google Apps accounts (school.com).

We're migrating our Exchange to Gmail over the summer and want our users to continue to login with their current Google Apps address, which is far easier to remember, but when they send from GMail we want the senders address to show as their official school email address (school.county.sch.uk).

Google has said that this has to be done on a per user basis and cannot be done domain wide. They did say there were tools in the Google Apps Marketplace that might be able to do this although would not provide specific details as they cannot provide support for them. They also said this could be coded using the Google Apps API, but I'd need to pay someone to do that.

Has anyone has this issue or found a way around it? Does anyone know an app from the Marketplace that will do what I'm looking for?

Thanks in advance for any help you can provide.