Outlook.com Data Lost After 2 Years of Inactivity
When performing electronic discovery for web based email accounts, keep in mind that a outlook.com account may become disabled if a user has not logged in for more than 2 years. After this period, may not be possible to recover the data for the account at all. Outlook reserves the right to delete the data.
See the services agreement posted here.
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OneDrive accounts will be closed after more than one year of inactivity. After a user voluntarily closes their email account, Microsoft will still permit it to be reactivated for another 60 days.