Exchange Admin Center

The Exchange Admin Center (EAC) at admin.exchange.microsoft.com is the web-based admin portal for Exchange Online. It's where administrators manage mailboxes (user, shared, room, equipment), mail flow (connectors, transport rules, accepted domains, remote domains), recipients (distribution groups, mail-enabled security groups, contacts), migration (cutover, staged, hybrid migrations), and anti-spam policies. Replaces the older Exchange Server Management Console for cloud-only tenants. Many configurations require Exchange Online PowerShell for scenarios the GUI doesn't cover — particularly bulk operations, complex transport rules, and custom mailbox settings.