2 Options

1. Download all email to PST and then export the PST to 365.
2. Use exchange and CSV of the mailbox to migrate emails over

If you have a paid license then you can create a shared mailbox on and it will not use an additional license. 

• How to make a shared mailbox
• How to access a shared mailbox
• The shared mailbox can also be set a password and logged in via a browser

• Godaddy Instructions

• Godaddy Instructions

• Add and manage multiple tenants

• Authorise Indirect Reseller

• Buy Microsoft 365 Basic