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Go to Files > Account Settings > Account Settings, choose second account, click Change...
Select All for Download emails for the past:
Close the tab. Go back to your Outlook inbox, right-click on your second inbox and select Copy Folder
Select your first inbox (username@uwaterloo.ca)
Click OK. It will start transferring your email.
Your old email will appear as a subfolder named inbox under your inbox. You should rename it to something to be more clear.
To You can verify online that the transfer was successful by visiting microsoft365.com
Sign in to the first inbox (username@uwaterloo.ca) to check for the emails
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