Gather information from client of how many mailboxes and distribution group will be migrated.
Add records on the domain registrar's website.Prepare your domain for migration by verifying ownership.
Preparing Exchange Server for mailbox migration
Use the Global Administrator account for your Microsoft tenant for preparation
up to 5 days
Start the Migration of the mailbox data, including contacts, and calendar & distribution groups & contacts.
Remediate any migration failures. Each mailbox sync can take anywhere from 20 minutes to 1 day depending on the size of the mailbox and the amount of attachments in the mailbox. Mailboxes are synced concurrently. They will each take their own time to complete.
Finalize the migration of the email data and update the necessary online records.
Time allowance for all changes in email to take effect.
Make Outlook find your new email automatically
Close off all connections to and turn off the on-premise server
Decommission and stop using the on-premise exchange server according to Microsoft best practice.
Notifying and introducing end users to the new Microsoft Office 365
Send a welcome email to your end users welcoming them to their new Microsoft email