Outlook Meeting Invites between computers on different servers

I would like to send a meeting invitation using Outlook Calendar to someone that is using Outlook on a computer that is operating from a different server.   The other person receives the invite, but they do not have an option to accept the invitation, which means that they have to reply to my email and re-enter the information on their computer.  Is there some way to send out these meeting requests to other computers that are also operating with Microsoft Outlook such that they are given the 3 options to accept, tentative, or decline?

Thanks, Espen