The light mode is usually quicker on slower computers and has a “Web Mail” style interface instead of a rich “Desktop” style interface.
To change to Outlook Web App Light, click the Options button, then See all options in your mailbox.
In the Options page, click Settings then General. Under General, click Use the blind and low vision experience. Click Save, then click My Mail, then logout and login again to use Outlook Web App Light.
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