The Data migration page shows various common email providers that you might be migrating data from, as well as giving you a convenient link for uploading a PST file.
There are also many guides of various types for onboarding onto and migrating to various Office 365 services, such as SharePoint, Teams, OneDrive, and so on, and detailed instructions for migrating from Gmail.
If this is your very first experience with Office 365, quite probably, you'll want to skip the extra helping of antacids and get the assistance of a Microsoft partner to help you make the switch. Microsoft partners will bring the experience of many different migrations for many types of organizations, and will have the tools and processes needed to make your ...
