General features	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Maximum Number of Users	Unlimited	Unlimited	Unlimited
Mailbox Disk Storage Per User	25GB	Unlimited--25GB in primary mailbox, unlimited storage in user's in-place archive	1GB
Microsoft Exchange Online Protection for real-time multi-layered anti-spam and multi-engine anti-malware protection
24/7 Microsoft IT-level phone support

Planning and Deployment	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Hybrid deployment supported
IMAP migration supported
Cutover migration supported
Staged migration supported

Permissions	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Role-based permissions
Role groups
Role assignment policies

Message Policy, Compliance & Recovery	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Exchange online mailbox archiving
On-premise mailbox cloud-based archiving
Retention tags and retention policies
IRM using Windows Azure AD RM
IRM using Windows Server AD RMS
In-Place Hold for preserving deleted and edited mailbox items
In-Place eDiscovery for supporting compliance through search tools
Transport rules
Data loss prevention (DLP) policies for added compliance enforcement
Journaling

Anti Spam / Anti-Malware Protection	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Built-in anti-spam protection
Customization of anti-spam policies
Built-in anti-malware protection
Customization for anti-malware policies
Admin management - quarantine messages
End-user self-management - quarantine messages

Mail Flow	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Custom routing of outbound email
Secure messaging with a trusted partner
Conditional email routing
Adding a partner to an inbound safe list
Hybrid email routing

Recipients	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Disk space capacity alerts
MailTips
Delegation access
Inbox email rules
Connected accounts
Inactive mailboxes
Offline address book
Address book policies
Hierarchical address book
Global / Local address lists
Distribution groups
Global external contacts
Universal contact card
Contact linking with social networks
Resource mailboxes
Conference room management
Out-of-office replies
Calendar sharing

Reporting Features	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Microsoft 365 admin center reports
Excel reporting workbook
Web services reports
Message trace
Message delivery reports
Auditing reports
Unified messaging reports

Sharing & Collaboration	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Federated sharing
Site mailboxes
Public folders

Email Clients & Mobile Devices	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Microsoft Outlook
Outlook web app
Exchange ActiveSync
IMAP
POP
SMTP
EWS application support
Macintosh clients

Voice Message Services	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Voicemail
Third-party voicemail interoperability
Lync integration

High Availability and Business Continuity	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Mailbox replication at data centers
Deleted mailbox recovery
Deleted item recovery

Interoperability, Connectivity & Compatibility	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Lync presence information in OWA
Sharepoint interoperability
EWS connectivity support
SMTP relay support

Management & Administration	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Microsoft 365 portal access
Microsoft 365 admin center access
Exchange admin center access
Remote windows powershell access
ActiveSync policies for mobile devices
Usage reporting

Add-ins and Resources	Exchange Online Plan 1	Exchange Online Plan 2	Exchange Online Kiosk
Outlook web app web parts
Outlook add-ins and Outlook MAPI