Why Co-exist with another mailing solution ?

What is a Co-existence solution?

A Co-existence solution, as the name suggests, is a solution where 2 or more mailing systems work seamlessly together to provide a common/ shared address space (email domain name like acmecorp.com), a centralized directory for authentication and personal properties of entities (users, groups), and common contacts of all mailing systems to all users.… Read the rest