About Microsoft Outlook
The email backbone of almost every Microsoft 365 enterprise.
Microsoft Outlook shipped as Outlook 97 in January 1997, replacing Exchange Client and Schedule+ and folding mail, calendar, contacts, tasks and notes into one personal information manager. Today it sits inside Microsoft 365 across desktop, web and mobile, with the user's mailbox living on Exchange Online and the rest of the M365 stack (Teams, OneDrive, SharePoint, Copilot) plugged in around it. Outlook on the web, the new Outlook for Windows and the mobile clients all read from the same Exchange Online mailbox, which is the object that matters for reporting.
For most M365 shops Outlook is no longer just personal mail. It is where customer threads start before a CRM ever sees them, where shared mailboxes (sales@, support@, billing@) catch the work before a helpdesk takes it over, where distribution lists fan out announcements that nobody re-confirms, and where Inbox rules and mailbox-forwarding configurations quietly redirect mail to outside addresses long after the person who set them up has left. The Microsoft Graph Outlook surface exposes messages, mailFolders, attachments, events, calendars, contacts, mailboxSettings and messageRules through one API. That is enough surface to answer the operational questions IT, security and revenue ops only ask after something already went wrong, but it also reaches the most sensitive store of text the company has, so what gets pulled and what stays inside Exchange is a deliberate scope decision.