Microsoft Exchange Online is the system where all the main user actions happen. It is where the users have their inboxes, calendars, and other objects, and where they access the features they need for their daily tasks, either using a smartphone, tablet, or other device, such as a PC.

Exchange Online establishes some limits to avoid problems that could impact your reputation. For example, it's only possible to send 30 messages per minute from a user's mailbox. If you need to send email in bulk, for a marketing campaign for example, it is advised that you rely on third-party services or use a different system in another infrastructure.